electric cooling fan

[reggie]

has any body got an electric cooling fan fitted-in traffic my temp gauge goes right up to the top-i dont think its reading correctly because when ime driving it drops to top mark under the red one-it has a new radiator-and there seems to be plenty of drag on the viscous fan -and when running it spins away merrily-i was thinking of taking it off and fitting an electric one-it might help with mpg also-what do you think ?
Reg

[Cees Klumper]

Hi Reg - do a search for cooling issues, lots of good info here. I would not take my chances on the gauge not reading correctly, I don't recall that ever having been an issue - meaning it's possible that your gauge is correct and you are in danger of warping the cylinder head etc. The new radiator fitted could be an indication of a cooling problem; probably there's a new thermostat in there as well.
I recall there have been discussions of electric fans, I think the UK based Kenlowe brand is specialised in this departmet. But, really, you should not have to resort to that if the original system is up to par.

[jeffc280sl]

This was on my list of things to do until I installed a heater core bypass hose.  I've been using it for three years now and recommend it highly.  It's simple to do and effective.

[jacovdw]

Reg,

Have a look at this very informative thread by a fellow member in your side of the woods: http://www.sl113.org/forums/index.php?topic=5944.0

[jeffc280sl]

I had a small pusher fan and didn't find it very effective.  I think Reggie is speaking about a puller type fan in place of the mechanical fan.  Even a puller fan with any capacity has clearance problems with the water pump pulley.  This sidewinder seams like a good but expensive way to go.

http://www.sstechusa.com/xfan/fans.html

[SteveK]

I did the bypass and then also changed my 5 blade fan to a 9 blade fan I found on the net.  That combination made a huge difference in how the temperature acted on a hot day in Houston at a stop light. (it rarely lifts off the thermostat temp now)

[jeffc280sl]

Can I have some more info on the 9 blade fan?  I guess it bolts right up to the water pump.

Thanks

[reggie]

thanks all - what and were is a cooling by pass hose how does that work - i only got the car on friday drove home 218 miles no problem but the gauge seemed to be reading high-top mark under the red one-when i stopped in traffic it went right up-i also had the air con on-it was a very hot day-i pulled over to check things more than once-it seemed fine-on saturday i took it for an mot while it was ticking over for at least an hour it went up again but it wasnt boiling or anything-so i dont no wich route to take-by the way it passed mot-somebody has loved this car and spent a lot of money-ime very lucky it needs nothing but this small problem doing any help would be great - thanks for all the replies
 Reg

[jacovdw]

Reggie,

This topic has been discussed on a few occasions in the past, but have a look at this thread: http://www.sl113.org/forums/index.php?topic=5470.0

Hope this helps.

[Garry]

Reggie try this also

http://www.sl113.org/wiki/Cooling/RetrofitCooling

or go into the Technical Manual then into the cooling and airconditioning, then have a look at some of the components in the section for ideas on over heating.

Garry

[SteveK]

The 9 blade fan bolts directly to the fan clutch with the same 4 bolts the 5 blade fan uses.  I did have to trim about 1/4 inch off each blade to make it fit the shroud just right.

[reggie]

it looked like a new radiator but on closer inspection it isnt just highly polished like the rest of the car so i think i had better start there-theres a round dent where it has come in contact with a pulley so its had a minor bump sometime-looks a bugger to get at too-i suppose hood off etc-the air con radiator is in front of it so that wont help cooling-lots of bugs stuck in it so big clean up while its in bits-off on holiday fri for 2 weeks so it will have to wait until i get back- got a man coming tues to take photos and put them on here with a bit of luck-i cant believe the condition of this car-ime over the moon with it-been cleaning and fiddiling all weekend 
Reg
ps thanks everybody

[jeffc280sl]

Reggie,

Below is a post from 1997 describing the heater core bypass hose.  It's easy to install.

"There is precious little space available in front of the radiator for an electric fan. With the A/C condensor out I have installed an electric fan which works helps marginally at best.  I don't think the fan I chose will fit with the condensor in place.

MB sells a bypass kit which routes water from the rear of the head via the TTS outlet back into the radiator.  This is an option for you.  It is expensive but so is a head gasket. 

Last summer I installed tee fittings in the heater hose lines running to and from the heater core.  These tee fittings are connected by a section of heater hose effectively routing super hot water from the head bypassing the heater core (when the valve is closed) and back to the radiator.  When the heat lever in the car is moved to the heat setting hot water is routed through the heater core as before.  The heater still works fine for me with this setup. Basically this setup does the same thing as you do when you use the heat setting in the summer to circulate water through the heater core.  The difference is that you do not route the heat through an already hot cabin.  My engine temperature is maintained between 180 and 200 degrees or so.  My only concern is with the engine temperature in the winter and if it is high enough to reach an efficient operating temperature.  I don't drive it in the winter so I have not looked into this.  Maybe some other folks can add their thoughts about this."

Jeff C.
1970 280SL 4-speed

[DavidBrough]

Hi Reggie,

In the day most cars held temperature very well unless you had A/C or an early 280. I think the MB supplied by pass kit was made specifically because of original problems encountered with the early 280's. You don't say what car you have but if you have an A/C equipped early 280 as I do then they are the hardest to fix. I'm currently rebuilding mine and found that the waterways in the head and the top of the cylinder block were quite silted up so I’m hoping that may well make a difference when I get it going again and allow a bit more of a standard set up. Needless to say I have tried just about everything to keep my car cool and  in the end succeeded by using a twin fan set up with an electric pump for extra piece of mind. I did have problems even before I fitted the A/C which a single pusher fan and the much heralded heater bypass didn't really cure. That said, the heater bypass has cured the problem for quite a few people.

You should start with a new three core radiator and a good flush out before fitting any additional electrical assistance, it may also be a good idea to renew the A/C condenser as this will seriously affect air flow if blocked. If you do have to go further then try the heater bypass which is fairly very straight forward to make and fit. If that’s still no good then 2 Spal units are the best and I will look up the ones I have for you if you need to go that route.

[ja17]

Hello Reggie,
These cars never came from the factory with AC. Most were added by the  dealer before the car was sold. Many owners  (especially those in warm southern climates) have had to make some changes to keep their engines from overheating while in traffic on the hottest days.

Be carefull not to let your engine run in the red. You cam easily blow a head gasket and possibly ruin the cylinder head. If  you find yourself in danger of oveheating take drastic measures to keep the engine out of the red zone.  Turn off the AC,  first and as last resort you can also turn the heater on full blast. A little sweat, may save an expensive engine repair.

Look at some of the solutions others have found. Re-coring the radiator with a heavy duty core (additional row of cooling tubes) seems to be a popular solution. You may try some other simpler fixes first. Review the information already on this site and keep us up to date.

[paulr]

I'm quite keen to learn more about the 9 blade fan. Would you mind expanding your experience please including where you got it from. Thanks a lot.

[Jonny B]

I do not have A/C in my car, but I went with the re-core of the radiator over the winter, from two to three as Joe indicates. Wow, I am not sure I have spent money any better for a more noticeable improvement. I think I could even do a parade, with stop and go now.

[SteveK]

I found the 9 blade fan on e-bay.  I just looked on the net at you can find one at:

http://cgi.ebay.com/ebaymotors/Mercedes-250S-250SE-250SL-280-Fan-Blade-66-67-73-75-76-_W0QQcmdZViewItemQQhashZitem43a042fe21QQitemZ290451553825QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_3123wt_939

I have a 230SL with a 1971 280SL motor.  I recored the radiator with a 3 row and also did the mercedes bypass a few years ago.  The bypass did really level out the block temps, but the overal engine temp still rose up to the second mark pretty quickly when stoped in traffic for 5 minutes. I then installed the 9 blade with a new clutch and now it rarely lifts off the thermostat temp.  I'm not driving the car much these days because I'm living overseas but happen to be back in good old Houston for the weekend for a meeting so I'll get to test it again this afternoon in 100 degree heat.  The car has not been started for 2 months so this should be a real good test

[reggie]

Just got back off my holiday this morning-The first thing i will try is to recore the radiator and a new viscous coupling while ime in there-The car only did it once on a hot day sat in traffic on the motorway-But i dont want to worry about it again-Its a 1970 280 sl fitted with aircon from new-its on the options list-when it did do it i put the heater on hot & fan on max and turned the air con off-As soon as traffic started moving it went down so ime thinking air flow problems-Fan or radiator we shall see. got to bed 2am up at 8am in the garage took the cover off and went to get some milk-1 hour later came home went to make coffee mmm forgot to get the milk-so jumped back in it and then went to the shop again-ha ha-Then spent half an hour showing shop keaper the car-i love it
Reg

[paulr]

thanks Steve. I bought one. What clutch are you referring to ?

[SteveK]

Paulr, on the 280sl, there is a hydralic clutch between the fan blade and the engine.  In the attached picture it's the Meyle component in the middle of the fan. Its about a $70 item availabe from the same guys who sell the fan.  You can also get it at most of our usual suppliers.   FYI, I had to trim the plastic fan to get it to fit cleanly in the shroud.  I made a template for what needed to be removed, traced it on each blade and then used a sanding wheel to trim the plastic.  It was very easy.   Ran the car yesterday when it was 100 degrees out and the only time it lifted off the thermostat temp was aftre a long run on the freeway at 65 miles per hour and then into some stop and go.  Even then it never got more than about 1/4 way to the next white square.  The 9 blade fan definitely moves a lot more air.

[paulr]

thanks Steve,

I've ordered one of those too.

p