Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: DavidBrough on October 01, 2006, 11:50:32
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After experiencing the all too common overheating problems when stationary for some time I finally decided to try an electric fan which seems to have cured the problem and thought I would share the results as this may help others.
My engine was rebuilt recently and I took the opportunity to fit a three core radiator and felt that this would be the answer. Unfortunately not, after 15/20 minutes stationary at tick over in a 20deg plus garage up went the temperature heading straight for the red.
Popping the bonnet helped as did revving the engine to about 2,000 rpm but I was not prepared to put up with that. Once on the move temp always returned to normal within half a mile. All the usual settings for ignition timing, IP and linkage were checked and rechecked, the fan clutch was passed as healthy by the local cooling specialists who also carried out numerous tests as they were certain that it must be a head leak somewhere but all was OK.
Despite the fact that the UK is not that hot in the great scheme of things and my car does not have A/C It got to the stage where I could not trust the car in anything above mildly warm in case I got stuck in an all too common traffic jamb. I had to try an electric fan.
I purchased a 13” fan from kenlowe and my radiator guy soldered some mounting tubes through the radiator so I could mount the unit direct and easily remove it if needed. Finished fitting the fan today and let the car heat up to the mark just below red and switched on the fan. Within 4 minutes temp was back to 180, happiness.
I attach some photos of the installation which was quite straight forward. I favoured a simple manual on off switch to the automatic to keep it simple and let me be in control.
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David,
Looks as if you have the same setup with the electric fan as I have on my 220SL.
I would also be careful with the clearance between the fan and the grille.
I mounted the fan so that the moving part will be exactly within the barrel of the star on the grille.
I dont have a picture now, but can post one soon. I also mounted an evaporator in front of the radiator for the future installation of the A/C.
But this is a good idea to have a small electric fan in front to help our cars deal with the modern traffic and heat dissapation.
Walter Klatt
1967 220SL-diesel
1963 230SL-gas-sold
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Are you sure that the radiator is clean (inside). When I recently fixed mine I had to have the radiator completely re-cored. Running it off and on while repairing the rest of the car, I let it idle in the garage for and hour or more. My temp never went above 180 (about 179 to be exact). It has never gone above that while driving either.
Bill Simaz
'66 230sl
Back on the Road
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Hi Bill,
I had a new radiator fitted with a three row core in place of the original 2 row which I though might help but didn’t. The cooling shop also re checked it when soldering in the mounting tubes for the fan and confirmed there were no blockages. From reading the many post on this topic it does seem that some cars are more prone to overheating when stationary than others and you are one of the lucky ones. I’m just glad mine doesn’t have to put up with 40 deg temperatures as some do. Once on the move the big radiator soon cools things down but when the temperature was over 30 deg, as it was here in the summer, it started to heat up quite quickly when stationery. I just needed some peace of mind and this seems to have done the trick.
David Brough
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One more thing whilst I think about it.
Last year I fitted heat tape to the exhaust front pipes which actually made a very significant difference by lowering under bonnet temperature. I think this may be more significant for RHD cars as the manifold exits forward. However, I had to remove it when I rebuilt the engine this year as I damaged it.
As it turns out that was a good thing as the front pipes had corroded quite badly under the tape and would not have lasted very long at all. I have a mild steel exhaust which is in reasonable condition. When I have to change it I will fit a stainless system and will try the tape again at that time.
If anyone is using heat tape on a mild steel exhaust you may well want the peel a bit back and check for corrosion as mine was really quite bad in 9 months and about 4,000 miles of use.
David Brough
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quote:
Originally posted by bsimaz
... When I recently fixed mine I had to have the radiator completely re-cored ..... '66 230sl
Bill,
Our 230 engines don't typically have as much of an overheating issue. The owners can usually resolve them through "normal" means, like you did. The persistent & difficult overheating problem is with the 280 engine. Bigger cylinder bores + same block size = less space for cooling passages.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420
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Hi David
I have a 280SL and was reminded of the overheating problem the other day in Piccadilly. I looked at the Kenlowe site then checked out your photos. How does this look with the grille back on? Does it show? Was this the best solution do you think?
thanks
paulr
paulr
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Hi
I would really like to see this picture if it is available
quote:
Originally posted by waltklatt
David,
Looks as if you have the same setup with the electric fan as I have on my 220SL.
I would also be careful with the clearance between the fan and the grille.
I mounted the fan so that the moving part will be exactly within the barrel of the star on the grille.
I dont have a picture now, but can post one soon. I also mounted an evaporator in front of the radiator for the future installation of the A/C.
But this is a good idea to have a small electric fan in front to help our cars deal with the modern traffic and heat dissapation.
Walter Klatt
1967 220SL-diesel
1963 230SL-gas-sold
paulr
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Hi Paul,
I’m not sure the electric fan is an ideal solution as you can see it through the grill, I will take a photo and post it, but in my case it does seem to work and I’m not worried about being stuck in traffic anymore.
David Brough
1969 280SL
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Here are some photos of the fitted fan with the makers sticker and, after removing the sicker and painting the centre mount black. It was very visible to start with but once the sticker was removed and the centre painted black it's not too bad. I took pics with and without flash although the real world visibility is much closer to the non flash pics.
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David Brough
1969 280SL
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thanks David for the photographs, they really are helpful. I suppose it's not too bad and as I really can't stand the 'will she boil over' tension I feel in traffic much longer and as I live in central London, I'll probably have one fitted too. I will sleep on it for now.
Nice garage..I've lived in apartments smaller than that!
paulr
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I have a fan like David's and I suppose it is helps some. What happens if you open the valve for the heater core? I have added T fittings to both the inlet and outlet hoses of the heater core. I connected an hose between these fittings which allows hot water from the head to bypasses the heater core and cycle through the cooling process full time. Heat works as before although I can't say for sure if it is sufficient in very cold weather. A shut-off valve placed between the two fittings would solve that issue. One would need to manually open the valve in late fall and close it in the spring. The cooling performance of the engine is significantly improved with the bypass hose and fittings.
Jeff C.
1970 280SL 4-speed
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Thanks for posting the pics. It looks good to me and as a driver of a car that has overheated regularly, I know how frustrating it can be and you solution is well worth achieving peace for mind. Enjoy!
Ken G
1971 280 SL
Silver/red
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Hello,
Besides the manual on/off switch for this auxiliary electric cooling fan arrangement, has anyone connected the fan to some kind of temperature sensor controlled switch? This would prevent the driver from having to manually turn on the fan (especially if someone unfamiliar with this 'feature' is driving the car). I have an electric fan I want to install in front of the condenser, and I'd love to hear more about how this was wired into the system.
In addition, if the temperature sensor switch is installed such that it bypasses the ignition switch, then it would keep the fan running after the car has been shut off. I'm sure everyone else here has seen their car temperature climb up after the engine has been shut off. A temp-controlled switch would keep the electric fan running for a bit longer after shut-off and prevent the engine temp from rising too close to the red...
WAQAS in Austin, Texas
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My fan is controlled by a thermostat like the one you desire. It works fine but the fan itself provides marginal cooling. My wife's ML has a electric fans and and an electric water pump. Sometimes after the engine is turned off I can hear the puimp running for a short time. This is another area for me to look at sometime in the future.
Jeff C.
1970 280SL 4-speed
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Jeff, absolutely brilliant idea!
An electric water pump would actually help in all areas:
(1) While idling in hot traffic, lots of water-flow would keep engine temperature hikes in check (no need for revving the car up to 2000rpms while stopped at a light).
(2) After shutting off the engine, water flow would very quickly cool down the engine, conserving the battery (a lower water pump speed after shut-off would conserve battery power too).
Questions that need answers:
- Is there an electric water pump that would fit in the existing pump housing? (or perhaps we can fabricate an 'adapter'....)
- Would an electric water pump provide the equivalent water flow, as compared to the stock pump, at high RPMs?
- I presume one would use a different alternator belt (bypassing the water pump entirely)
- Power requirements: would it be wise to upgrade the stock 35A alternator to something more, say 55A? I was wondering about this for the addition of the electric fan as well. Of course, an electric water pump would be much more effective!
Have we missed anything?
This is a very very compelling idea... has anyone ever tried it?
WAQAS in Austin, Texas
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These are interesting questions. I think my ML as an auxillary electric water pump. Meaning there is a belt driven pump also. It is my belief the aux electric pump helps to cool the engine after shut down by continuing to circulate very hot water through (some part or all) the system. I don't know if it operates while the engine is running. Your idea goes a step beyond and suggest a full time elctric water pump in place of the mechanical one.
Jeff C.
1970 280SL 4-speed
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Electric water pump, what a neat idea. Had a quick look on the web and these people seem to do quite a few. Just search on electric water pump.
www.burtonpower.com
Would be interested to hear any other thoughts.
David Brough
1969 280SL Auto (with A/C almost)
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For those of us with air conditioning, there isn't room for this fan between the condenser and the grille. Has anyone done away with the fluid clutch and fan and put electric fans between the radiator and engine?
Ray
'68 280SL 4-spd Coupe
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Ray,
What is a fluid clutch?
Jeff C.
1970 280SL 4-speed
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Jeff,
That's the Visco fan clutch...
Bob
quote:
Originally posted by jeffc280sl
Ray,
What is a fluid clutch?
Jeff C.
1970 280SL 4-speed
bpossel (Memphis, TN.)
'71 280SL / '97 E320
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Hi Ray,
I’ve just fitted A/C and have had to remove the blower fan I fitted in order to mount the condenser. I found mention of a Spal puller fan in a previous post that some of our German friends have successfully used to replace the standard viscous unit so I’ve ordered one. The part number is VA18-AP51/C-41A which has a 63mm depth and should just fit. Unfortunately it will take about a month to arrive as this is a special order part in the UK. Will let you know how I get on.
David Brough
1969 280SL Auto
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Hi,
I have the overheating issue with my '71 280sl only when I am stuck in traffic for quite a while. I have read the posts about putting in a 3 core radiator and changing the fan. I have A/C in the car which I don't particularly use but do not wish to remove the condensor as some have suggested just yet.
Where can I order this larger capacity radiator & fan from? Thank you for your suggestions.
Bert
'71 280sl (auto-A/C)
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Hi Bert,
I purchased and installed an after market high efficiency radiator and it didnt help much. I then took my original MB radiator to a local radiator shop and had them add the extra core. Using my original radiator with an add'l row has worked well and is what I would recommend.
I also installed a new Viso fan clutch (fan). Purchased from Arizona Autohaus (https://www.autohausaz.com). They have it listed currently for $162.
Good Luck,
Bob
quote:
Originally posted by pch90265
Hi,
I have the overheating issue with my '71 280sl only when I am stuck in traffic for quite a while. I have read the posts about putting in a 3 core radiator and changing the fan. I have A/C in the car which I don't particularly use but do not wish to remove the condensor as some have suggested just yet.
Where can I order this larger capacity radiator & fan from? Thank you for your suggestions.
Bert
'71 280sl (auto-A/C)
bpossel (Memphis, TN.)
'71 280SL / '97 E320
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quote:
Originally posted by jeffc280sl
These are interesting questions. I think my ML as an auxillary electric water pump. Meaning there is a belt driven pump also. It is my belief the aux electric pump helps to cool the engine after shut down by continuing to circulate very hot water through (some part or all) the system. I don't know if it operates while the engine is running. Your idea goes a step beyond and suggest a full time elctric water pump in place of the mechanical one.
Jeff C.
1970 280SL 4-speed
Actually, that's what I thought you meant in the first place. However, installing the pump as an auxiliary unit may have it's own advantages. In the case of adding another pump as an auxiliary unit, some questions:
- Where does it get attached? (in the head-to-heater-core outlet path, perhaps? This assumes that your neat trick of bypassing the heater core is employed...)
- If so, it's temperature control mechanism would need the heater lever to somehow also contribute to switching it on/off)
- Would one pump running in 'series' with another alter the flow of the other? In other words, once the engine is switched off, would the electric pump be strong enough to pull water past the now-stationary mechanical water pump? (or is there some other way to bypass the flow)
This is getting complicated, but good food for thought. Once I've sorted out my radiator re-coring project, I'll have to revisit these ideas...
WAQAS in Austin, Texas
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FWIW -
When I bought my '69 280SL about 2 years ago, the cooling system *didn't*. I was able to get it home at a reasonable temperature by opening up the heater valves (in 90 degree heat!) and maintaining highway speeds.
I went through the entire process:
1 - new thermostat
2 - electric fan: MB part, thin, mounted in front of the condensor, black fan/painted black retaining nut. Barely visible, but if you look for it through the star, it's there. It is wired to come on with the a/c, and does so very nicely. Didn't solve the problem.
3 - High efficiency radiator (eBay, $250): Looks stock, car now *rarely* exceeds 180deg, even in this weather.
If anybody wants pictures of the electric fan install, I'm happy to share, but may take a day or two.
-Reed
'69 280SL Silver/Blue
'92 500E
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I do have to say that the more I look into this electric water pump idea the more intriguing it gets. Some more useful information at www.mawsolutions.com
I will give them a call when I have time for a good chat and see what they have to say.
David Brough
1969 280SL Auto with A/C
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Interesting ideas from Mawsolutions. Another thought to consider is installing a smaller diameter pully on the mechanical water pump. A 20% decrease in pully diameter will create a 25% increase in shaft rpms.
example:
pump pully diameter engine rpm waterpump shaft rpm
5 inch 750 1200
4 inch 750 1500
I think the idea for cooling the engine at idle is to pump more water. A smaller pully accomplished this. It would also move more water at higher rpms which could be problematic I suppose.
Jeff C.
1970 280SL 4-speed
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I struggled with cooling issues for a while before sending my car up to Gernold. He went through the entire system but the overheating issue was still not completely fixed but then what seemed to work was moving the temp sensor to a different location on the engine block.
Normally the temp senor is near back, because the car would get warm when stopped at a light but instantly get cooler as soon the it started moving (before coolant from the radiator had a chance to make it to the block), Gernold surmised that perhaps the sensor was in a corner of the engine that was hotter than the rest. Sure enough, when he moved the sensor to the front of the engine, the temp gauge is much slower to move into red.
If that didn' work his next endeavour was to install an electric pump to circulate coolant when at idle but the problem appears to be solved unless I am stopped for extended periods in very hot weather.
I understand from Gernold that the electric pump solution has worked well for another member of this forum who had been experiencing chronic overheating.
Ken G
1971 280 SL Silver/red
1969 BMW 2800 (sedan)
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From the Mawsolutions website, it appears that installing the electrical pump in series with the mechanical pump is feasible (and recommended by them). However, they recommend placing the pump in one of the two radiator hoses (upper or lower). Questions:
- If placed in the upper or lower radiator hose, won't the fan be useless (and possibly under risk for burnout) when the thermostat is closed?
- Of course, if the thermostat is close, additional cooling is not required, so perhaps the fan's cutoff switch should activate at the thermostat temperature?
- Would it not be more useful to attach the pump in series with the heater inlet hose, with a bypass hose fitted from heater inlet to outlet? (bypass courtesy of Jeffc280sl)
In my car, placing the pump in the lower radiator hose is not really possible-- there's too much stuff there already! (A/C compressor, idle pulleys, belts, etc, etc). This is still a good idea for preventing the engine from heating too much after switch-off.
WAQAS in Austin, Texas
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Was chatting with retired MB mechanic about overheating on the 113's
and also 250 68 - (his personal car).
They (MB Mech) would drill 3 - 4 holes - 1/8 dia in the rim on the
theromstat and this would correct the overheating problem.
Ron - Minnesota
71 280SL Tobacco "O GIGI"
03 525 BMW BlACK/BLACk
97 E420 Silver Mist
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Ron,
This would imply that the stock thermostat does not allow enough water flow. If this is true, I wonder why MB has not caught on after 40+ years of the same thermostat design for these cars... surely by now they should have modified the design to allow more flow?
WAQAS in Austin, Texas
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There are many things un said in the big blue book that are not
changed and should have been changed.
Some methods in the BB make it hard than it really is ex.
change the front coil spring. Follow the book they say remove the 4
bolts on the lower arm. Much easier - remove the lower bolt from
the king pin.
It's those BULL HEADED GERMANS ( and I am one of them)
Ron - Minnesota
71 280SL Tobacco "O GIGI"
03 525 BMW BlACK/BLACk
97 E420 Silver Mist
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It should be noted that the standard thermostat is 87C for most aplications as I believe this thermostat is used on quite a few different cars in cluding Diesels. The correct thermostat for our cars is 79C which will give you a running temp of about 180F. 87C will get you up into the 195 - 200F range on a hot day while just driving along at a speed of 60 MPH. I had to special order the 79C thermostat and now I have 180F and picked up about 10 PSI oil pressure at idle. Don't let your car run hot for any reason - it WILL warp the head over time.
Dan Caron's
SL Barn
benzbarn@ebtech.net
slbarn.mbz.org
1 877 661 6061
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Well, my new engine fan has now arrived and been fitted in place of the standard viscous unit and first impressions are very favorable.
I thought it best to post the results here rather than in the A/C thread even though the change was occasioned by the fitting of A/C.
For a little bit of history, I had been experiencing problems as originally posted here in that my cooling system worked very well until I stopped, at which point things started to get very hot until meaningful progress was again possible.
My original solution was the fitting of a 13inch blower fan to the front of the radiator which solved the problem completely (at least at UK temperatures).
I then had the notion that I wanted to fit A/C which I duly did but had to remove the pusher fan in order to fit the condenser. As a result I was back to square one with an extra heat source to cope with on top. When I purchased the A/C I had already decided to replace the standard engine fan with an electric one but, as the one I needed was not available in the UK I had to wait until yesterday for it to arrive from Italy. In the meantime I tried the heater bypass modification used by jeffc280sl but whilst that did keep the engine cooler on the move it made little difference when stationary on a hot day with temperatures still rising quickly towards the red. So, the electric fan had to work or I was in trouble.
So, I removed the radiator (I’m getting quite good at this now) and sent it to the local radiator shop to have mounting sleeves braised in and a thermostatic switch fitted. At that stage I also decided to source a small fan for the A/C condenser and found an 8 inch blower fan than would just fit. In the end I had to bend the back of some of the grill fins to get it to fit but in it went. I mounted this on a small piece of wood as a spacer on the front cross member to take the weight with the top mounted through the condenser fins on plastic ties which seem to be standard mounts for electric fans. Sorting out the wiring was more trouble than I thought but I made things work in the end with a couple of relays.
The A/C fan now switches on when the A/C is in use and the engine fan cycles in and out when necessary. I currently have a 92/82 thermostatic switch and 79deg engine stat fitted and so far that works OK (26degs today) with the fan staying off whilst on the move and cycling on/off when stationary or in traffic. Need to do a bit more testing in more arduous conditions but my car in standard trim would have overheated today in about 15 minutes if stationary and the fan was able to keep things cool on its own and with the A/C on.
The fans fitted were SPAL units as follows:-
Engine puller fan 16”/385mm part VA18-AP10/C41A
A/C pusher fan 7.5”/190mm part VA14-AP7/C-34S
The A/C fan would only fit directly behind the star with the engine fan having to go high and right on the radiator due to the power steering pump.
I enclose some photos of the installation which may be of interest.
David Brough
1969 280SL Auto with A/C
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Hi David,
;) Your installation looks very neat and clean and well thought out.
Please keep us posted as you drive in stop & go traffic and summer heat.
8) fyi... Memphis heat has been tipping the 100's for the past 2 weeks and looking on Yahoo weather channel, they are predicting 107 by Wed.
:D Bring your car here and we can really test it out...
Regards,
Bob
bpossel (Memphis, TN.)
'71 280SL / '97 E320
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David, nice setup! I have to say, in my case the heating problem has practically disappeared since I had my radiator re-cored (three row).
The temperatures in Austin are now in the high 90's daily, so I'm getting to drive the car with A/C almost everyday. Without A/C the temp holds at 180, and with A/C, it hovers between 185 and 195 (estimated) in stop and go traffic. When I turn on the heater bypass (with the A/C running), the temp stays between 180 and 185. Of course, the A/C is a bit less effective with the heater bypass enabled...
Sometime this winter, I plan to install Jeff Clute's nifty heater bypass hose solution within the engine compartment (using a couple tee fittings between the heater core inlet and outlet hoses).
Waqas ('Wa-kaas') in Austin, Texas
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OK so its summer again and I’m still getting a bit hot and bothered so I decided to try an electric water pump from Davis Craig. www.mawsolutions.com
I purchased the EWP80 which was a bit of a tight fit but went in eventually and I’ve just wired it to come on with the electric fan, not had a heat wave to properly test it but so far it seems OK.
I think if you wanted to fit one with the standard fan it may take a bit more plumbing but as I have an electric one it slots straight into the bottom hose. Will let you know how I get on when it gets a bit hotter.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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Looks great. Did you mount the pump to something, or is it simply 'floating' between the two ends of the cooling hose?
Please keep us posted as to performance.
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It sort of floats in the bottom hose but rests quite firmly on the air filter inner panel due to space constraints. At this stage I have put some rubber in between to stop vibration damage and will have to keep an eye on it.
David Brough
1969 280SL Auto with A/C and 3.46 Axle
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The best car is the 250SL. Lots of cooling room in the block and the largest rad of all 3 cars.
Try using a 79C thermostat. My car runs at or below 180F even on the hottest day. Excessive heat is VERY bad for these engines.
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Hi Dan,
I have the 79 deg thermostat and whilst I have never actually overheated I’m not comfortable about heavy traffic on hot days.
Only real test at this stage has been to let the engine get nice and hot then switch it off which usually then adds a good few extra degrees and puts the gauge almost onto the mark above 180 and just below the red, but 10/15 seconds of the electric fan and pump together has it straight back to 180.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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How much power are the two fans drawing? Did you have to upgrade your alternator?
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Is this stationary in warm weather "overheating" problem particular to the 280SL?
My 250SL with 14k miles since rebuild, plus recoring radiator, doesn't have an overheating problem and this is in 100F+ weather and after high speed (80mph) driving and coming to a stop right off the freeway. Fan clutch engages sometimes after coming to stop after high speed freeway driving in 100F+ weather... but temperature gage never even comes close to the red area.
Since 250SL and 280SL engine blocks differ only in bore/stroke, and if bore's larger on the 280SL then cylinder cooling efficiency is better than the 250SL anyway (thinner walls means faster and more efficient tranfer to heat to water passages).
I submit therefore that any overheating problems means something's broke ---- pump wear causing insufficient coolant flow, or scale build-up in water passages in block or radiator increasing resistance to coolant flow... hence reduction in coolant flow volume, or oil pump efficiency loss (even if oil pressure gage says all's ok).
If overheating's a particular problem on 280SL's then what is the design difference that pushes the 280SL over the edge compared to a 250SL? Recall that MB shipped a ton of the W113's to climates much hotter than Germany... not insignificantly a higher proportion geographically to US SoCal area where summer time temps are relatively high all the time. If overheating was an issue with reliability or function MB would have had to change designs to fix this by the time the 250SL and 280SL especially started rolling off the lines.
All the work/effort/modifications to improve coolant volume or air volume over radiator seems to me to be masking some other problem(s) that need to be corrected anyway. If engine's producing more heat than it should be for the designed water pump volume flow and radiator (heat exchange), then it means engine's frictional heat sources are exceeding the design limits... i.e. bearing wear and/or cylinder wall wear.
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Hi Werner,
I’m not actually sure what the amps are for each fan but I do have three. The main fan a slimline Spal must be about 10/15 with the small condenser fan being about 5/10 and the evaporator fan about 10/15 perhaps. I do have an uprated alternator fitted but don’t know its rating off hand but I do tend to plug in a trickle charger when the car’s not in use.
Longtooth,
I agree with your sentiments but it does seem that the early 280’s were quite susceptible to getting a bit hot and bothered and MB changed the head design on later cars which seemed to cure the problem, they did bring out a kit for the early cars but those that have tried it say it’s not much good and very expensive. I have replaced everything possible in mine and added numerous upgrades but all to little avail. As I don’t think MB changed the pump design it seems to be more a circulation problem which, so far at least, the electric pump seems to have resolved. Having said that it also seems unlikely that my car behaved this way when new and I do know that the problem is not A/C related as I had the same issue before it was fitted so something must have changed over the years but quite what, apart from fuel, I don’t know.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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quote:
Originally posted by Benz Dr.
The best car is the 250SL. Lots of cooling room in the block and the largest rad of all 3 cars.
Try using a 79C thermostat. My car runs at or below 180F even on the hottest day. Excessive heat is VERY bad for these engines.
Does the 250SL have an oil cooler? Is the cooler controlled thermostatically? Maybe the bigger radiator is the answer?
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quote:
Originally posted by DavidBrough
Hi Werner,
I’m not actually sure what the amps are for each fan but I do have three. The main fan a slimline Spal must be about 10/15 with the small condenser fan being about 5/10 and the evaporator fan about 10/15 perhaps. I do have an uprated alternator fitted but don’t know its rating off hand but I do tend to plug in a trickle charger when the car’s not in use.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
Curious about the evaporator fan. You have that inside under the dash?
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The heater bypass isn't pretty but works well on my 280SL.. keeps the temp right around the 180 deg. mark, even on hot days in traffic or mountains.
Download Attachment: (http://images/icon_paperclip.gif) heater bypass.jpg (http://www.sl113.org/forums/uploaded/Dick%20M/20087112138_heater%20bypass.jpg)
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I think I got the idea from Jeff C.
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Dick,
When I fitted my A/C I also fitted a heater bypass, exactly the same as yours, and the Spal fan on the radiator in place of the viscous unit on the basis that together they would solve the problem but still no joy. What I don’t know however is if they would cure my problem without A/C. I did take a bit of a punt when fitting the A/C knowing I had an issue but felt the problem must be curable.
It has been a bit warmer over here today and I left the car ticking over long enough to overcome the electric fan and start to get gradually hotter up to the middle of the two marks on and above 180 then switched on the pump and bingo down to 180 again, I just hope it continues to do the same when temperatures get a even hotter. For the time being I have wired the electric pump to a manual switch so I can monitor what is happening and if all proves OK I will link it back into the automatic switch for the fan.
Werner,
The evaporator fan is the standard blower that came with the Buds underdash unit and I think oil coolers were only fitted as standard on 280’s. At one stage I did think about looking at either a larger or an additional oil cooler as they can make a lot of difference, hopefull I won't need to go that far.
David Brough
1969 280 SL Auto with A/C & 3.46 Axle
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Thanks for the info. I think a larger oil cooler might work but it gets pretty cold here winters so I would need to install a thermostat. Its been pretty hot here recently and I over heated my M130 engine. Now it smokes badly (oil smoke) when first started after sitting awhile. I just had a valve job a couple thousand miles ago. Don't want to fix it until I determine what caused the problem and don't want to drive it while smoking. I already had the radiator rodded out and that didn't seem to make much difference. The car does not have a condenser fan so that will be the next step. Also I might go with a rotary AC compressor instead of the stock York compressor. Wouldn't the heater bypass cause the cabin temperature to get uncomfortable?
quote:
Originally posted by DavidBrough
Werner,
The evaporator fan is the standard blower that came with the Buds underdash unit and I think oil coolers were only fitted as standard on 280’s. At one stage I did think about looking at either a larger or an additional oil cooler as they can make a lot of difference, hopefull I won't need to go that far.
David Brough
1969 280 SL Auto with A/C & 3.46 Axle
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The 250SL has an oil cooler (water/oil heat exchanger) mounted under the Fuel Injection Pump beside the block.
As for differences in engine heat/cooling capacity between the 250SL (M129 II engine) and 280SL (M130 engine), the 280SL's increased bore required the cooling water jacket between Cyl pair 2 & 3 and between Cyl pair 4 & 5 in the M129 to be omitted in the M130 engine. The M129 had an 82 mm bore while the 280SL's bore is 86.5 mm.... both engines used the same stroke (78.8 mm). Another difference is that the 280SL's fuel injection pump uses oil from the block... whereas the 250SL uses it's own oil supply. The 280SL also uses a different cam design than the 250SL but I don't have access to the specs on valve opening closing timing for the 280SL so can't determine if the difference in cam designs adds or reduces to heat build-up.
The 280SL's increased engine horsepower also meant it produced more heat... larger bore means more piston wall area for friction of rings on cylinder walls increased by 5.5%. The elimination of the water jacket between the 2 cylinder pairs on the M129 engine to accomodate the increased bore on the M130 engine also decreased the conductive metal volume between those cylinder pairs as well as the others... which decreases the thermal heat carrying capacity from the cylinders... so a double whammy in terms of removal of heat from the cylinder wall on the M130 engine (280SL) relative to the 250SL's engine.
Most of the heat removal from the M130 engine cylinders is removed by the water passeges in the head... which by the way is also the hottest portion of the cylinders --- nearest the combustion chamber and exhaust passages in the head.
I don't know what MB design engineer's did to increase the cooling capacity for the M130 engine however... I'd guess, but have no documentation, that coolant flow rate and volume would have had to be increased (larger capacity water pump). I don't know the 280SL coolant capacity but the 250SL uses 12.9 liters, while the 230SL's uses 10.8 liters (a 19% increase in coolant volume on the 250SL over the 230SL).
It's possible, therefore, that from an engine design point of view the 280SL's increased bore and eliminated cylinder coolant jackets to accomodate it coupled with the increased heat generated in the higher horsepower engine means that it has less margin with any restrictions or reductions in coolant or pump efficiency to maintain coolant temperatures with lower (idle) rpm and hot exterior environment. The lower rpm with car at standstill means less air/water heat exchange at the radiator and reduced coolant flow volume thru the block and radiator at the same time. Unless the 280SL uses ~20% more coolant and a larger capacity pump (greater volume flow rate) it's likely that the 280SL (M130 engine) would be more prone to heating coolant to higher temperatures with low engine and car speeds than the 250SL.
Ref: Engelen's book, pages 176, 180, 181, 182 and Service Manual, Modification Oct. 67, 0-3/7 , 0-3/8 (i.e. specs).
Non-thread comment: I guess that may be another reason why the early 250SL's are the crem de la crem of the W113's.
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quote:
Originally posted by Longtooth
Non-thread comment: I guess that may be another reason why the early 250SL's are the crem de la crem of the W113's.
:) In my creme de la creme, the temp gauge is practically pinned at 180 no matter how cold or warm outside.
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quote:
I agree with your sentiments but it does seem that the early 280’s were quite susceptible to getting a bit hot and bothered and MB changed the head design on later cars which seemed to cure the problem, they did bring out a kit for the early cars but those that have tried it say it’s not much good and very expensive. I have replaced everything possible in mine and added numerous upgrades but all to little avail. As I don’t think MB changed the pump design it seems to be more a circulation problem which, so far at least, the electric pump seems to have resolved. Having said that it also seems unlikely that my car behaved this way when new and I do know that the problem is not A/C related as I had the same issue before it was fitted so something must have changed over the years but quite what, apart from fuel, I don’t know.
I have an overheating problem as well, when idling in drive. In N the problem doesn't seem to occur. Maybe I have the wrong waterpump pulley, or using a pulley with smaller diameter would cure the problem. I'd like to try that.
Does anyone know of a part number or engine type which uses a smaller pulley? I know most Mercedes engines from the 60's and 70's all use the same 4 hole water pumps.
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You get an auxilary water pump from a 123 or 126 and mount it in one of the lines.
These things work by pushing coolant through the heater core on 126 cars while the car is sitting at idle. The regular water pump on the engine doesn't have enough power to feed all the coolat lines on these cars.
Should work great on our cars and could be set up to turn on at a certain temp or throttle position.
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Dr. Benz:
Would I need to install a heater bypass in order for the aux pump to work in hot weather? Is there a temp sensor in the block I could connect it too?
Also, would you have any ideas as to what caused my M130 to start smoking after I overheated it?
quote:
Originally posted by Benz Dr.
You get an auxilary water pump from a 123 or 126 and mount it in one of the lines.
These things work by pushing coolant through the heater core on 126 cars while the car is sitting at idle. The regular water pump on the engine doesn't have enough power to feed all the coolat lines on these cars.
Should work great on our cars and could be set up to turn on at a certain temp or throttle position.
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Get an auxillary watter pump from a 123 or 126 and plumb it in line with a heater hose. Since it's electric you can hook it up to work only at idle or at higher coolant temps.
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quote:
Originally posted by Benz Dr.
Get an auxillary watter pump from a 123 or 126 and plumb it in line with a heater hose. Since it's electric you can hook it up to work only at idle or at higher coolant temps.
Dan,
what is your take on doing the heater bypass...really effective...cause problems?
Thanks for your many contributions..
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Hello all, I have for the past year been enjoying (testing)operating temps @ 180F instead of freaking out as the gauge heads north towards red.
I made two T fittings, one from 11/4" steel pipe, and 3/4" pipe, (inline upper S radiator hose) and the other T made from 3/4" pipe (inline to heater) mounted the water recirculating pump from 123 or 126, utilized a 4 pole working relay, connected to the lower terminal of the throttle body switch.
It has been my intention to put this in the R&D section with a step by step including pictures, just trying to find the time. I can say that after doing everything else (4 row radiator, new fan clutch, water pump, totally rebuilt and cleaned engine) this is the ONLY solution that has actually worked (for me).
Mine is a late model 280sl with automatic and a/c, overheating is a common problem and I have read most of the posts. Your radiator has plenty of cooling capacity. The problem is that the heat is not being taken away from the cylinder head quickly enough at idle or stop and go traffic. I am now able to drive the car in Dallas 96F ambient(120 off the pavement), and temp 185-195F in stop and go.
It works so well, that I rarely look at the gauge anymore! The only drawback, it now takes about 7-8 min for the car to warm up where the idle drops, instead of 3-4min. A small price to pay. In cooler temps, I just disconnect the electric water pump so that it doesn't run at idle.
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Markus:
Would I need to install a heater bypass in order for the aux pump to work in hot weather? Is there a temp sensor in the block I could connect it too?
Also, would you have any ideas as to what caused my M130 to start smoking after I overheated it?
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Was ist los(Penna Amish)? Chock one up for shady tree engineering. Will those Germans ever learn?
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I've never had to do this set up so I'm not the best one to ask.h However, logicaly you would have a benifit from moving coolant through an area that has little flow at idle. The 123 coolant pump would be ideal for this job and it's designed to take the heat. The problem is that there's little coolant flow around the back of the head and block when the engine is idling and there's no air flow around the oil pan at all. Roughly 40% of your cooling is done by oil running through the engine and that heat has to go somewhere once it's produced. This is why the 250SL has the absolute best system when it comes to cooling - it has the biggest rad of all three cars and it has the water/oil heat exchanger. This is not an oil cooler but it is a heat exchanger .
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I would also look at putting a 79C thermostat in for summer use. In very hot weather my car just starts to hit 82C while driving at higher speeds. It never gets much above 84C while sitting for over a 1/2 at idle. Standard trans cars also run much cooler.
Any car with auto and AC should use the 79C thermostat.
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Benz Dr. -- fwiw, the 250SL water/oil heat exchanger is called an "oil cooler" in the MB parts description. I just today looked into availability from both my local MB dealer's parts dept and MB CLassic Center in Irvine. Both locations documentation blow-ups parts list and describe it as an "oil cooler".... since it's purpose and reason d'etre is to cool the oil.
If you bypass the oil cooler ... i.e. connect the input and output coolant lines to one another so that no coolant enters the exchanger, the engine heats up more at speeds when the engine's working harder... i.e. oil runs hotter because the engine oil isn't being cooled at all by the coolant thru the heat exchanger.
This was a quick and dirty design fix to the 250SL engine's heating due to it's increased displacement over the 230SL's, even though the M129 (250SL engine) has coolant flow between 2 pairs of it's cylinders. The problem with the 250SL's oil cooler was that it was insufficient for the 280SL (M130) engine's oil cooling requirements which lost the coolant space between the 2 pairs of cylinders due to it's increased bore plus it added hp and thus higher thermal dissipation over the 250SL's engine. The 250SL's heat exchanger is also in a difficult place to remove/replace if it developed a crack... i.e. higher labor content.... hence the change to the 280SL's oil cooler (on the sides of the radiator) covered the issues well enough for an engine without it's coolant passages or oil passeges obstructed -- but with the 280SL engines now approaching or exceeding 40 years of use in varying degrees, these passages are often-times partially blocked... especially the coolant passages... by calcium deposit build-up over time... not to mention rust related obstructions. Hence, the acceptable and required level of cooling in the 280SL's cooling capacity is reduced significantly in this circumstance. The addition of a fan at the radiator to augment the air/water heat exchange at the radiator compensates for the ruded coolant volume flow thru the engine.... especially at idle or low engine speeds without car's motion forcing additional air volume thru the radiator.... as well as lower coolant volume flow at idle.
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Following what appears to be a successful cure for my overheating I thought it worthwhile posting what I have gleaned about “normal” operating temperatures and what MB say about it. The table below I think gives a good summary of what happens when but I can give no guarantee as to the accuracy of individual temperature gauges, which may vary:-
Deg F Deg C Action
135 75 MB noted minimum normal operating temp
174 79 Summer thermostat opens
180 82 Marking on most gauges (considered normal operating temp by many)
187 87 Winter thermostat opens
194 90 Viscous fan starts to fully lock
203 95 Viscous fan fully locked & MB noted max normal operating temp
212 100 Next mark on gauge above 180 dot
239 115 Red dot and MB noted max allowable temp and pressure cap blow point
250 121 Top mark and overheated
Most gauge marks are therefore 180 – 212 – 239(red) – 250 or 82 – 100 – 115(red) – 121 and MB say that normal operating temp is 135/203 or 75/95 with stints up to 212/100 acceptable and usual in heavy traffic. The maximum permissible temp is the red line at 239 or 115, the limit of the pressure cap. However, if you reach this level, the cap will blow and the water will boil so don’t go there.
The upshot of all this is that our cars can and often do operate up to the dot above 180 i.e. 212 or 100 without concern, just don’t let yours go above it.
I now have a 95/90 temperature switch for my electric fan and pump which keeps things neatly under control.
David Brough
1969 280SL Auto with A/C and 3.46 Axle
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As per Dr. Benz' advice, I took an electrical water pump off a 124 and will install it soon. I am thinking of a seperate switch, just to see which is more effective, the electric water pump or the fan.
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Hi Ziggy,
I tried a small 20ltr/min pump in the heater bypass line and found it made little or no difference for me. The pump I have in the bottom radiator hose is 80ltr/min and has a much more profound impact on the temperature. It cuts in at 95 degrees and removes 5 degrees in about 10 seconds. I think it will take a bit longer with higher temperatures but the fan on its own struggles to reduce the temperature by much at all and just can’t cope when things get really hot. In addition, the pump will also work with the engine turned off to eliminate any chance of heat soak which is also very reassuring.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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quote:
Originally posted by Q45Denver
Would I need to install a heater bypass in order for the aux pump to work in hot weather?
It would appear so, as where would the coolant go if the heater was switched off? The real question is, does it make better sense to bypass just the the heater (thereby re-circulating), or from the back of the head to directly to the upper radiator hose?
quote:
Is there a temp sensor in the block I could connect it too?
I'm sure there's such a temp sensor on the M130, but is there such a thing on the M127 and M129 engines? Do these sensor signals have any hysteresis? This would be useful in order to avoid rapidly switching the pump on/off when the temp is floating around the trip point. Or am I over-analyzing this? (don't answer that)
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If you want to install a pump in the heater circuit you will need to also install a bypass line for it to work with the heater off. The one I tried just fed back to the normal water pump housing by the bottom hose and wasn’t very effective. A feed to the top hose may be more effective but would require some degree of additional modification and would also bypass the thermostat.
I don’t think there are any existing temperature switches that could be used but there are a number of devices available that are a simple fit into the top hose to control fans and pumps. I had the top casing of my radiator modified so a standard temperature switch would screw in and it works fine. Temperature switches usually operate with a throw of 5 or 10 degrees depending on application and I’ve found that an on at 95 degrees and off at 90 degrees works for me. I first had a 95/85 but once on that almost never switched off so I tried a 92/87 but that was still an over high cut off so I ended up with the 95/90.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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Hi David
I'm sorry to keep bringing this up, but can you give us your definitive thoughts on the use of an additional switchable electric water pump, without the extra fans etc. If one's car is working "normally" with everything having been checked, like radiator and fan yet still in City hot traffic gets worryingly hot, does the fan make a difference ?
Both Roger Edwards and Kevin O'Keefe wont fit one or even consider the heater bypass and just say that our cars dont need it but traffic was different in those days and although everything has now been done to mine like HE radiator just cleaned out, fan bought up to scratch etc it still gets hot when sitting in traffic and I just can't keep turning up the heater and revving the engine.
Fancy fitting one for me?
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If your cooling system is marginal you may also try running straight distilled water and some Water Wetter should be good for about 10 degrees.
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Paul, I have a radiator with extra cooling core, heater bypass, electrical fan and recently build in an electrical water pump.
The summer is over here, so I haven't been able to test it really well but it seems the waterpump on it's own (has seperate switch) seems to do little in a traffic jam. Combined with the electrical fan (put on at the right moment) it seems to be able to keep the temperature at around 90 degrees C in D. In N I don't need the fan or the waterpump, even though the revs are only about 200 rpm higher..
Do you have the newer type oil pan? This is supposed to make a noticable difference. I'm planning to install one in the near future.
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Hi Ziggy,
What does the oil pan do, where is it and how does it contribute to cooling ? Would you mind explaining please.
p
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A finned oil pan sounds interesting and would certainly add to the cooling capacity but I doubt it would make much difference when stationary as there would be no airflow. What you need is either extra water flow or air flow or both.
I found the electric pump fitted in the bottom hose to be excellent even cooling the engine without the fan when the car is stationary. Once on the move it’s not really needed as normal air flow always brings the temperature down below 90 even on hot days. I’m so impressed with it I’m going to remove my electric fan and put the standard viscous unit back as I think that would be the ideal set up. All I have to do is work out the plumbing as it’s more tricky to fit with the standard fan. I’m also going to try changing my existing 79deg thermostat for an 83deg one to stabilise the temperature a bit as I’m so confident in the ability of the pump. I think we may sometimes think these cars should run cooler than they do because we’ve mostly fitted 79deg thermostats and forget that when new UK cars came with an 87deg thermostat so normal running temperature would be 90c or 194f not the widely quoted 180f which is just 82c. A 79 deg thermostat can give some wide fluctuations in operating temperature as the system is effectively overcooling in some circumstances and this is what fuels overheating concerns. The issue is just controlling temperature rise when there is little or no natural airflow through the radiator.
Ziggy, I see that your electric pump didn’t seem to work well, did you fit it in the heater bypass or the bottom hose and what make and capacity is it? I tried a 20ltr pump in the heater by pass and it made no difference at all but an 80ltr pump in the bottom hose works very well.
Paul, sorry to hear you are still having problems. I would be happy to help you fit an electric pump once I’ve worked out how to fit it with the standard fan. If you still have my number give me a call or e-mail me.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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The new type oil pan is deeper than the old, increasing the amount of oil in the engine. I'm not sure by how much but I thought it to be approximately 1 liter. This is important as something like 50% of the cooling is actually being done by oil.
As per Dr. Benz' advice, I took an electrical water pump off a 124 type. It is a Bosch I think, don't know the flow per minute but it is only a small pump which can not be fitted in the radiator hose, therefore it had to be fitted at the heater bypass.
I can see why a big 80 liter/minute pump in the radiator hose would make a big difference.
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Any one know the approximate flow rate on the stock water pump? Hpw big a job is replacing the oil pan?
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David, which 80 ltr/min electric pump are you using?
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David, I do and I will call you. It might be something for the new year.
p
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My pump is a Davis Craig made in Australia and I it got from these people www.mawsolutions.com
I think the problem with the smaller bypass pump is that it only circulates already hot water round the engine as it can’t break the pressure of the engine pump to push more water through the radiator which is the only thing that will increase cooling.
Paul, that’s fine, I should have worked out how to fit it with the standard fan by then.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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What's the advantage of the standard fan over the electric? I know they sell electric ones that have the same or more CFM's.
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I fitted an electric fan a while ago to try and get some extra pull at tick over as they always run at full speed. However, due to the slim nature of the unit needed to fit, the extra air flow was marginal and, whilst it was better, it was not the cure on its own. In addition, its activation is very specific in that it is either on or off at set temperatures unless it’s linked to a very fancy progressive controller which I’m not bothered about trying to fit. The standard fan on the other hand is progressive and starts to lock up at 90c with full speed gained at 95c. At the moment I have the pump and fan linked to a 95/90 temperature switch which works well enough, now I have the electric pump, which can quickly reduce the temperature below 90 and switch everything off. Now I know I can control the temperature I feel that the standard fan offers the best alternative as it will start to lock progressively from 90 whereas the electric set up lets the engine run straight up to 95 before kicking in. I did try some lower start temperature switches but as the smallest throw is 5c they were trying to overcool the engine and sometimes didn’t switch off for a long time and, starting the cooling at over 95 is not really recommended. A bit long winded I know but in general the standard fan set up works well and only really kicks in when needed so, on balance, I feel that this, with the electric pump linked to a 95/90 switch, would be the best setup. However, the proof will be in the pudding and I have yet to try it but from what I’ve seen so far this should be the best answer. The only real problem is the space available to mount the pump with the standard fan fitted as the electric unit sits on the radiator there is much more room for the pump. I’ve purchased various hose bends and some aluminium joiners and will see if I can get it to fit with the standard fan and report back.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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I'm starting to think that all electric might be the way to go. This would also free up some horsepower and result in a freer revving engine but might require an alternator upgrade. While the current setup is fairly robust it is not doing the job in traffic and when going up mountains which we have a few of in Colorado. A fan controller is fairly inexpensive and simple to install so that should not be a problem. The controller might also allow the engine to operate within the narrow temperature range as designed. I have a single Spal 16" puller fan with a shroud that might do the job. My car does not have a shroud currently installed. Either it did not come with one or was removed by a prior owner. Or I might visit a local wrecking yard and see if I can find a fan out a late model V-8 that might fit.
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Hi Werner,
The fan I have is a slimline 16” Spal unit and whilst it does give a bit more pull at low engine speeds I think the standard unit moves more air at higher revs. The standard size 16” fans just won’t fit. I have to say that my engine is much quieter with the electric unit but, as it won’t do the job for me on its own, I would like to run the standard fan set up with the electric pump if I can. Also, being a viscous unit it doesn’t put such a strain on the engine until it has to work hard. A fan shroud should certainly make quite a bit of difference but, due to space constraints, the Spal unit has to go high and right on the radiator so any shroud may have to be custom made. Space is particularly tight on my car though as I have A/C and the condenser means that the radiator has to be mounted well back towards the engine. If you don’t have A/C you may find that you can create a bit more space by pushing the radiator forward as the mounting points are slotted and allow quite a bit of movement and you may be able to get a more central mounting position.
Don’t know about the V8 fan but I would expect it to have quite a large and powerful motor which just wouldn’t fit. Space is a real issue.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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I haven't played with it yet, but space should not be much of an issue as I intend to get rid of my mechanical fan entirely. I do have A/C but can't use it much of the time due to overheating. Another thing my car is lacking is a pusher fan on the front for the A/C condenser. I have one from a W126 model which should fit. I will install it inline with the other fan so they both come on at the same time I guess.
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Hi Werner,
I think you may find that space is a real issue and only the slimmest of slim line fans will fit on the engine side of the radiator. There is space on the right side by the alternator but the water pump pulley is in the way of anything near the centre and the power steering pump obscures the left side quite badly. Fitting a fan on the condenser is a good idea but you are probably better off wiring that to come on with the compressor.
David Brough
1969 280Sl Auto with A/C & 3.46 Axle
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David,
So your saying even with the mechanical fan removed, there is a space issue? I have an M130 in a 1969 W111 coupe (mechanically the same as your W113). I think If I can set both fans to come on at variable speeds depending on the temperature, that would be ideal. Somehow with the summer almost over, this project is starting to lose some priority. Did you notice any gain in heater operating efficiency with the electric pump installed?
quote:
Originally posted by DavidBrough
Hi Werner,
I think you may find that space is a real issue and only the slimmest of slim line fans will fit on the engine side of the radiator. There is space on the right side by the alternator but the water pump pulley is in the way of anything near the centre and the power steering pump obscures the left side quite badly. Fitting a fan on the condenser is a good idea but you are probably better off wiring that to come on with the compressor.
David Brough
1969 280Sl Auto with A/C & 3.46 Axle
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Hi Werner,
I didn’t leave the small pump on long enough to find out if it increased heater performance, as it did nothing for the cooling I just removed it again. It’s quite likely that a W111 has more space available to fit a full size fan which I suspect would be able to provide sufficient cooling as they move about 25% more air than the slimline versions.
David Brough 1969 280SL Auto with A/C & 3.46 Axle
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Well, I’ve now removed the main engine electric fan and refitted the standard viscous unit with the electric pump which went in very easily in the end. I’ve also removed the heater bypass and replaced the thermostat with an 83c one and now it’s not warm enough to get the engine hot to trigger the pump so I’ll have to wait for a better day to properly test the set up. With the electric fan the engine would run up to the fan trigger point (95c) relatively easily but the standard unit needs much more severe heat before it starts to lose control which is one reason why I think this will be the best solution. I’m off to France in a few weeks with a better chance of hot weather so I’ll let you know how I get on.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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David, would you be kind enough to post a picture or describe the location and mounting of the electric pump, when you get a chance?
Thanks.
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Hi Andy,
Here are some pictures of the pump with the electric fan fitted, I will take some with the standard fan tomorrow but the mounting hasn’t changed. I first though I would have less room for the pump and would have to be creative with its positioning but in the end I just removed the electric unit and fitted the standard one back without touching the pump mounting. Fitting the pump is very straight forward; I just cut into the bottom hose and fitted it in.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
Download Attachment: (http://images/icon_paperclip.gif) Pump1.jpg (http://www.sl113.org/forums/uploaded/davidbrough/2008815161348_Pump1.jpg)
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Download Attachment: (http://images/icon_paperclip.gif) Pump2.jpg (http://www.sl113.org/forums/uploaded/davidbrough/200881516147_Pump2.jpg)
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Download Attachment: (http://images/icon_paperclip.gif) Pump3.jpg (http://www.sl113.org/forums/uploaded/davidbrough/2008815161426_Pump3.jpg)
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Download Attachment: (http://images/icon_paperclip.gif) Pump4.jpg (http://www.sl113.org/forums/uploaded/davidbrough/2008815161457_Pump4.jpg)
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Thanks David!
Is the pump fixed/mounted to anything, or does it just "float" on the hoses? (can't tell for sure by the pix)
Did you get the Thermal Switch?
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Hi Andy,
I’ve take a picture of the pump with the standard fan but I think the other ones give a better view as the fan gets in the way.
The pump just floats in the standard bottom hose although it is a bit tight against the bottom of the air filter panel so a put a small piece of rubber in between.
I use a standard M22 fan switch to trigger the pump which I had tapped into the top of the radiator but you could use any of the proprietary switches which fit in the top hose. There are lots available with different temperature ranges but I found 95/90 to be the best.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
Download Attachment: (http://images/icon_paperclip.gif) Pump.jpg (http://www.sl113.org/forums/uploaded/davidbrough/200881625910_Pump.jpg)
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Download Attachment: (http://images/icon_paperclip.gif) Switch.jpg (http://www.sl113.org/forums/uploaded/davidbrough/200881625933_Switch.jpg)
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Today I got into a huge 70 minute traffic jam, couldn't go any faster than 5 miles or 10 km p/h. :x It was 80 degrees and sunny, which always led to overheating combined with this kind of traffic. It was the first time that I could try the 124 electrical pump together with the electric fan under these conditions, and I am happy to say that it kept the temperature steady just above 80 degrees all the time :)
Did anyone ever get any results with water wetter type products btw ?
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I think it’s about time for a cooling update; the best laid plans and all that.
During the summer I decided to try the electric pump with the standard MB fan as I felt that this may be the best option. However, whilst this did work OK it was definitely not as good as the electric fan. I think this is because the standard fan just doesn’t pull through the same level of air at low revs as the electric unit which is always at full speed. Additionally, the electric fan and pump set up can be engaged with the engine off giving dramatic results whereas the electric pump on its own i.e. with the standard fan, is not so good. On balance I think the electric fan and pump set up is best so I’ve now swapped back. I also changed my 79deg thermostat for an 83deg one which the engine seems to prefer as it maintains temperature much better. With the lower one I would see some quite wide variations at the gauge but things are much steadier with the higher one.
David Brough
1969 280SL Auto with A/C & 3.46 Axle