Control Valve/Heat Sensor - Haynes

[n/a]

I want to extend the warmup period on my 1965 230 SL.  I have the third version on the start mechanism - page 07-1012a BBB.  On top of the injection pump, I have the coolant thermostant and no inlet air thermostat. On a cold start the purpose of my coolant thermostat is to mechanically connect with the rack in the IP to enrich and to open the atomizing jet on the base of the coolant thermostat.  Have I got that right?

To extend the enrichment time I want to increase the distance that the thrust rod must travel???
So to extend this enrichment process do I (Hanes Manual page 72, Fig. 3.64) a) increase the thickness of the gasket at 3  b)remove a compensating washer at 6 or c) add more compensating washers at 10?

Hope some of this makes sense.

Rupert

[jeffc280sl]

Rupert,

I believe your explanation is correct.

I happen to be looking at this issue right now with my 1970 280SL.  I'm not sure your car has the same setup as mine.  Probly does not as these items are emission related.  There is a low coolant temperature switch that removes vacumm pressure on the distributor when the temperture is below 62.5 degrees F.  In doing so the idle increases.   Figure 3.90 of the Haynes manual shows the device.  It is normally closed and switches to open when the temp goes above 63.5.  Mine is open all the time so I get no benefit when the temp is below 63.5.

No one seems to sell this switch online.  I think it is broken on many cars and people just forget about it.  No demand = no supply.

Good luck

Jeff C.
1970 280SL 4-speed

[Ben]

Unless I am very much mistaken, please speak up, all the 113's have similar cold start systems with one coolant filled thermostat which when cold allows extra air in and also pushes the rack in the injection pump forward. The nett effect of more fuel and more air is higher idle speed. As the motor gets warmer the thermostat heats and the little spud on the end is forced out shutting off the air and pulling back the fuel pump rack. Therfore to increase the duration of this cycle you need to increase the number of washers at the base of the thermostat !

Guys have I got that right ehh ?

The above is totally seperate from the shot of fuel you get at the cold start valve on the manifold whilst cranking !


Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[George Davis]

This system is refered to as the Warmrunning Device in my 280 SL BBB.  All W 113s have a Warmrunning Device, with the early systems being a little different than the later ones, but otherwise functioning similary (or so I believe).  The latest US 280 SLs switch off sooner.

According to the book, 07-14 section F in the 280 SL BBB, to extend the time this system operates before shutting off you need to remove compensating washers where the thermostat element pushes on the air valve, inside the device (shown as 6 in my book).  The larger compensating washers at the base of the device (shown as 10) are for mixture adjustment.

George Davis
'69 280 SL Euro manual

[ja17]

Hello,
Tread carefully here, changing the settings for the warm-up device will also change the fuel mixture of the injection pump in all speed ranges and temperatures! Other pump adjustments would be required to counteract adjustments inthe warm-up device.

Joe Alexander
Blacklick, Ohio

[n/a]

Warmrunning Device

I would like to find a good article on the warmrunning device as related to the injection pump.  I checked my BBB which covers cars from 1959 to 1967 and there is no mention of this device/activity.  I also checked my other books with no results.  Could any suggest a book that might discuss this aspect of warmup.

Thank you for your help and advice on this topic.

Rupert 1965 230 SL

[George Davis]

Joe,

I'm looking at a diagram of the warmrunning device, and it seems to me that if a shim is removed from below the thermostat (at 6 in diagram), then all of the internals (air valve and guide pin) move up by the thickness of that shim, which means the control arm in the IP also moves up the same amount.  Now, if the same thickness shim is removed from the base of the warmrunning device (at 10 in diagram), would that not move everything back down to where it started and therefore not affect mixture?

In other words, if a shim is removed in one place, then also remove the same thickness shim at the other place, and there is no net movement of the end of the guide pin.  In this way, Rupert can extend the operating time of the device without affecting mixture throughout the entire range.

Does this sound right?

George Davis
'69 280 SL Euro manual

[Ricardo]

Perhaps this isn't the correct place for this question but it relates to the thermostat being disscussed here. I have a new thermostat to install but the construction varies slightly from the old one and the fit to the dished metal spacer is poor. I'll enclose a couple of photos to make this clear. I do remember reading that it is neccessary to enlarge the hole in this spacer to allow the thermostat to seat properly. Before doing so I have tried to find info in the archives relating to this but haven't found the discussion. Can anyone confirm that it is proper to enlarge the hole, since it seems difficult to assemble with the setup as is.
Ricardo

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[ja17]

Hello George,
Yes, you must compensate for any change you make in the distance that the plunger travels into the injecion pump in order to keep the mixture the same after warm up.

Joe Alexander
Blacklick, Ohio

[Ricardo]

I'm a little confused as to how the device effects mixture after warm up. It seems that the plunger is pushing down against spring pressure and this results in opening the extra air intake and advancing the rack. As the thermostat reaches operating temps it should contract and reduce the downward thrust. Does the plunger not contract completely, so that it no longer has any effect or is the device supposed to push down a certain amount all the time? I have found that the new thermostat is working the same as the old and that removing washers in either location seems to have no noticeable change, I still have a small amount of suction at the filter inlet. I'm thinking that I need to add washers at the base, to raise the plunger up so as to allow the rack to fully return. Or am I confused as to how this works
Ricardo
P.S. the parts number for the thermo from MB is A 001 203 95 75

[ja17]

Hello Recardo,
The warm up device thermostat extends downward into the pump as the coolant temperature increases. As it extends, it moves the slide valve, which begins closing off the extra air intake. In addition a pin extends into the injection pump where it acts on the rack to decrease fuel supplied to the injectors.
Unfortunately as you have found, the replacement parts are not always identicle. You may have to just install it and see how it does. The thermostat fit up is a compression fit. The air supply through the little injection pump air filter should close off shortly before full warm-up (see BBB for temperature). Ajustments can be made from there. There may be a Mercedes technical bulletin on the subject somewhere who knows?

Maude points out also that there is no clear discussion of the mechanism. The BBB tends to jump around between many models and gives model specific reference only in bits and pieces. The information is then scattered throughout the 400 pages of two or three different factory manuals. Often times retrieving the information takes longer than the fix! There is a lot of valuable information to be gained from the text but you have to dig for it and sometimes read between the lines. The value of this group is that eventually we will fill in between the lines and organize everything into a W113 specific technical manual.

Joe Alexander
Blacklick, Ohio

[hands_aus]

Hi Ricardo,
Measure the lengths of the rods on each thermostat.
They will need to be the same length when cold.
I found that I shouldn't open the hole of the collar because the length would have changed too much.
I fitted a new thermostat just like your new one by centering the collar and adding a film of silicone sealer to the water side of the thermostat then centered the housing with the screws.
It works.


Bob (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Ben]

Yes I've read a few different manuals on this system and I still havent found a schematic which shows the way the early 230SL is set up !

The early cars have a different thermostat and it is integral with the Housing. I dont have ANY washers/shims between the Thermostat Housing and the Sliding Air Valve Housing, and I dont see where they would go either !

I DO have shims UNDER the Air Valve Housing, between it and the Pump body !

I figure that INCREASING the distance between the protruding spud and the Valve means that as the temperature rises the increased distance means that the spud takes longer to hit the Valve and shut off the air/withdraw the rack. Effectively you are increasing the time the Warm Up Device operates.

If you remove shims from UNDER the Air Valve Housing you are advancing the fuel rack and increasing idle speed slightly, however the rack is now slightly more advanced even when warm, which is why the mixture needs to be reset elswhere !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Ricardo]

I appologize for hi-jacking this thread....I don't think I've helped to clear Rupert's queries at all, though we are talking about the same components. I guess my notion that this thermostat was contracting against spring pressure was mistaken and as Joe and others have pointed out the spud will expand as it is heated, therefore I now think that the shut off position must be some where in between. When you install this assembly you are compressing a spring, you must push the unit down against internal springs to insert the screws which hold it to the injection pump body. If the thermostat pushes down as it warms, the spring is being further compressed and the correct shut off position is somewhere short of the full compressed position. In my case I can't completely shut off the suction at the filter. I have tried removing the bottom oval shims from 4 to 0 and still have suction. I have only 1 shim at the tip of the thermostat and removing it produced no change as well. The next attempt will be to add small shims at the thermostat and see what this produces. If Rupert needs to increase the duration of warm up, I beleive the BBB says to remove small washers at the thermostat (6)to "retard" the warm up device. Hopefully we will eventually have a clearer understanding of how this is supposed to operate.
Hopefully I won't break anything trying  
Ricardo

[Ben]

After some advice from Joe Alexander last year my car was running and starting very well, although it always needed throttle.

However I knew there was no washers between 'stat and the air valve housing so yesterday, after all this talk, I took it off slowly and I could feel the spring pushing it up quite a bit. I felt that the spud was forcing the valve down all the time quite a bit. So I found a copper washer that just fit under the 'stat !

RESULT !

The car now starts from cold straight away with no throttle and it idles at 1100RPM. I've checked that the air valve shuts off, it does, and the hot idle is 800RPM. I'll check later with a CO meter !

I've tried it twice from cold and also some hot starts in between and its better than ever !

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[knirk]

After reading your reply Ben, I started to think (that happens once in a while).

After the engine was rebuilt this winter I had to adjust 16 clicks to get the idle up to 800 rpm. I asked my mechanic in Norway about this and he felt it was strange, but couldn’t think of why. Obviously there is more shear resistance in an overhauled engine, but the increase was way more than this should call for. When I start driving (from cold) the engine responds very quickly to the gas pedal. I can feel less and less response as the engine warms up. It runs great, but I need to give it more throttles. And it backfires when revving down passing 1500 rpm.

I had the CV/HS housing and heat sensor off for cleaning, but did not touch anything further down in the heat valve. But I realize that I could easily have missed any compensating washers in this process, and installed it with maybe one missing.

What kind of washers do we talk about? What size? Are they available as a spare part?


Per G. Birkeland
69 280 sl aut 834
Norway

[Ricardo]

There are two different washers being discussed here. At the base of the "warm running device" where it connects to the injection pump housing there are large oval washers with two bolt holes and a bigger central hole, like a small exhaust manifold gasket from a lawn mower, approx. 2" or 5 cm. across. The second type is a small washer that fits into an aluminum housing that the actual thermostat pushes against. To get to these you have to unbolt the upper  screws that are holding the thermostat housing and then remove the aluminum cylinder below the thermostat which is down in the body of the unit. I found a magnet was the easiest way to lift this cylinder out as the center washer is steel. This part normaly slides up and down with the change in the thermostat length. When you get the aluminum cylinder out you have to remove a small circle clip from inside the cylinder to remove the black metal washer. Below this are the actual shim washers. They are very thin and perhaps 1/2" or 1.25 cm. in diameter. It is obvious by the thickness of these that small changes are all that is neccessary to alter the duration of warm up.
I'm glad to hear that Ben was able to see a marked change with only one washer added, though I don't believe the originals are copper, we are talking a couple of thousands of an inch thickness on the original steel washers. The BBB states that the black washer should be on top as it is fit to the thermostat spud or tip.
I have included two pictures showing the internal components and the location of the small shim washers
Ricardo
An update: I have added a thicker washer as I only had one small  thin one and the dealer didn't show these on his computer, so I gave up looking for them from MB. Sometimes the parts are very difficult for my parts guy to locate as the schematics from MB are terrible for mixing up the locations of various parts i.e. when we tried to find the fuel filter on his system yesterday, it was not located with the fuel system or the injection pump but in a separate file called "intake muffler" which included the air filter and the fuel filter. Anyway with the original thin washer and a thicker one the suction is pretty much gone, and I hope that I finally have the "warm running device" shuting off. I think that a CO2 meter is going to be my next purchase as I don't have confidence that the vacuum method of setting idle speed and mixture is very reliable. I agree with Chuck that in order to prolong the warm up time that Rupert should remove a small washer IF his 230 actually has them which I suspect it doesn't,
By the way, I found that it wasn't neccessary to drain the cooling system if I disconnected the top hose to the inj. pump thermostat and opened the rad cap. The coolant level was low enough if I didn't let the thermostat housing hang down too much and I only had a couple of drops then. Be careful though, we don't want coolant in the inj. pump
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[bayleif]

I have some experiance with this device as "I played around" with the thing for about a year before I could get my newly acquired 280SL to run. It was not my only problem, but it but it was a major player.

First, just to make the terminology clear, when Rupert says that he wants to extend the enrichment time, I interpret that as he wants to increase the temperature at which the warm up device shuts off. To accomplish this, remove washers from the little pin on the end of the termistat since as the termistat expands with heat it shuts off the warm up device.
Now I always assumed that once operating temperature was reached, the actuator of the warm up device would "bottom out" so that regardless of the number of compensating washers the "fully off" position would always be the same. If that were true, then the two adjustments would be independent. Adding or removing washers to the thermistat (6) would change the temperature at which the device shut off but not effect the fully warm setting and adding or removing washers at the base (10) would adjust the richness through out the warm up time but also when fully warm. Then, you could adjust the fully warm state first (10) and then worry about warm up.
However, this assumption may not be correct. The thermistat may expand until it's force is equal to the force of the spring it is compressing or it may just expand to it's limit. In either case, adjusting this thing gets a whole lot more complicated.
Ricardo, I drilled out the spacer. According to my assumptions, any difference in the length of the pin was going to be adjusted by the washers (6). I was also trying to deal with the same symptoms as you. No matter what I did, the stupid thing would just not shut off. It turns out, after replacing the thermistat ...twice, and playing with the washers (6) for months that my problem was that the thermistat housing was not getting enough water flow to actually get hot enough to shut off. The coolant return line was plugged at the banjo fitting just underneath of the engine thermistat housing. Check this, the warmup device should get "hot". Not just warm to the touch.


Chuck Bartlett
1969 Signal Red 4 Speed

[Ben]

Okay thanks to Chuck and Ricardo, good photos BTW, I see where there is a difference !

Firstly the 230SL has a different thermostat, its all one piece integral with the housing, I think we knew that. You wont loose any coolant by opening it either. However as discussed breifly elsewhere there is a small 14mm bolt, with a roll pin fixing, on the side of the air valve housing. The end of this bolt has a tiny spud which extends into the air valve chamber and it was stated that this was a diagnostic feature which enabled the mechanic to manually close the air valve totally, and therefore illiminate this from the equation.

The reason I bring this up is that I dont know whether or not the 280SL is like this, but this pin and bolt needs to be removed totally before the air valve can be removed as it physically holds the spring,loaded air valve in the bore.

So.......I didnt remove this bolt as I believe they are easily broken and the pin looks hard to remove. Instead I placed a copper washer directly between the thermostat housing and the top of the air valve housing. This is where I had always assumed they went !

Now as you can see I have lifted the 'stat by ADDING washers thereby increasing the length of time the system stays active, whereas you guys are ADDING washers allowing the air valve rise higher and therefore cut off earlier !

The question still remains, is the actual Sliding Air Valve the same on 230/250/280's and should the washers therefore be the same and in the same place ! Leave aside the shims UNDER the Air Valve housing as these appear to be identical!

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[knirk]

Hi Joe,

I am still a little confused about the function of the CV/HS valve. My 280 engine is running good. It is running very good until it is warm. Thereafter I need more throttle to have the same response, and that’s why I looked at what you wrote in the Pagoda113.com discussion page:

“You can richen up the injection mixture on all speed ranges by removing one or more of the metal shims between the warm up device and the injection pump /oval with three holes).”

I ran out in my garage and took the valve apart. I did not find any shims or washers - you can look at the pictures. Is the shim you mention in the text suppose to be between the thermostat element and the bracket left on the IP, or have I completely misunderstood?


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Per G. Birkeland
69 280 sl aut 834
Norway

[Ben]

You have removed only the thermostat housing. You now need to remove the rubber hose and the two screws that hold down the air valve housing. When you've done that you can lift it off and the shims become visible, be careful as you may lift them with the valve. They are quite thin but substantial enough that you wont loose them.

I'd suggest removing the thinnest one, then reassemble, drive the car see how it behaves and if neccessary try again. If it does drive properly then you will need to get the CO measured and readjusted by means of turning the air screw on the inlet manifold or the mixture screw at the rear of the pump with the engine switched off !

Sorry if I've stated the obvious................I just kept typing !!

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[knirk]

Thanks Ben,

I will hoist down in the garage again.

Per G. Birkeland
69 280 sl aut 834
Norway

[knirk]

I found two shims between the valve house and the injection pump. Tried to remove the thinner, but didn’t get any improvement. Put it back - together with a paper shim made of emery paper (just to try). No big difference, but no improvement. I adjusted the idle CO for each try. The level went from 4.5 to 1.3 after the thin shim was removed.

I am no back to start. The engine runs OK, but still with more throttle needed for response after it is warm. I can live with that.

The last time I had the valve house off, I did it without removing the thermostat. I didn’t remove the two waterhoses – just the lower air hose and the two screws, and managed quite easily to remove a shim without any mess with cooling water.


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Per G. Birkeland
69 280 sl aut 834
Norway

[ja17]

Hello knirk,
Did you try running it with both the shims removed? If the car coughs back through the intake during acceleration  this can be a sign of a lean fuel situation. Removal of the large oval shims leans out the fuel mixture in all speed ranges. Adding the large oval shims shims richens the mixture. For temporary testing just loosening the screws richens the mixture and does the same thing as adding shims.
Normally these injection pumps wear "rich" with age. Shims can be removed to lean the system.
Have you considered the posibility that the injection pump may have been installed out of time during the rebuild?

There is also a main rack adjustment which also controls the pump mixture in all speed ranges if you run out of adjustment with the shims. Don't go here unless you are sure about everything else.

Joe Alexander
Blacklick, Ohio

[W14]

Ben, to answer your question:

No, I am sure the air slides are not the same, since mine (older) does not have the plunger and parts visible in Ricardo's pictures.  My air-slide has no washers for adjustment - instead, there is a small dia. bolt that you can screw in or out to change the effective length of the air-slide plunger.

Also, the temp. bulb and the housing are indeed separate pieces. There is a slight flare/friction fit at the base, the same as the newer style.  I used some silicone there at re-assembly.

Another, perhaps more convenient way to experiment, is to add/remove washers under the baro. compensator (need a thin 17mm to remove).  It is a "finer" adjustment than the WRD (.10mm shim under WRD will move rack approx. .12mm; .10mm shim under baro. will move rack approx. .10 mm).

Here's a pic. I made when I was fiddling with mine.

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Will W14
1965 230SL 4spd
Victoria,BC