280SL Engine stalling when warm

[Thierry du Laos]

Hi,
I have a gear auto on the car. When i drove a while and the engine is steady warm in temperature, in the traffic the engine stalls when I have to stop the car in the traffic. Its not the power brake, because its been restored and has no more leak.
I have no problem to go to Neutral and restart, drive again and go....
I wonder where is the problem?
Just looking on the injection pump I saw a pressure capsule with the water cooling system going through.
I suppose that this assy has to deal with the temperature and fuel injection control???
Could it get stuck, and make my trouble. Or its for a different purpose?
Is it a frequent problem already often experienced?
Thanks.
Thierry

[ja17]

Stalling when warm  can be caused by a lot of issues. Check to see if the WRD is functioning correctly. Check to see that your tuning is correct (points, dwell, timing, wires, plugs etc.) Make sure your engine linkages are correct. (linkage tour).  Make sure your fuel supply is correct (filters, pressure, volume etc.).  Check the fuel mixture when the engine is hot.  (split linkage test).  If you find that your fuel injection is too rich or lean when warm, get back with us on the fix. Do the other checks first. If any of these tests are not familiar with you do a little research here or get back with us for more help.

[Pawel66]

Does it stall only when you have D or R engaged? Or it stalls in N or P as well?

1. If the idle in P or N is nice when warm and it stalls when in D or R - you do not have idle increase mechanism working properly maybe (it usually is the constant speed solenoid, but can be something else). If your idle is not nice (e.g. below 800rpm, uneven) when warm in P or N and it stalls when you engage a gear - see point 2.

2. If your engine stalls when warm also in P or N or the idle is not nice - there is something wrong with idle - as Joe said - need to go through the usual routine of ignition time, dwell, plugs, linkage tour. I would say: electric things to be checked first, then fuel related (unless it is clear fuel is not there).

[Thierry du Laos]

Hi,
Sorry, what is the WRD?
I had previous problems with the constant speed solenoid, that i fixed. I can engage D and R without any problem when cold.
In fact everything is fine when cold.....
I will check the richness again.
And need to swapp with an other coil too.
Lets see further, thanks for the first ideas.

[Thierry du Laos]

OK, sorry again I've got it:

https://www.sl113.org/wiki/Engine/WarmRunningDevice

I'll check also its filter as on the chapter above.

[Thierry du Laos]

Update...
I removed the WRD. I think the valve was stuck.
But after cleaning and re-assembly, I can still hear airflow at the filter when the engine is warm.
When I tested the thermostatic element it extended 5 mm. Is that enough to close the valve?
Does any one knows the element total length once completly extended?

[mrfatboy]

If my memory serves me correctly the total movement of the thermostat pin should be ~6mm.

Length when cold: ~18mm
Length when hot:~22mm

[ja17]

Thierry, did that help the stalling problem?

[Thierry du Laos]

Not really solved.
Maybe a little.
So Next I will add washers in the piston of the valve to make sure it closes 100% when hot.
Because, anyway, here in Laos tropics,  the engine is never really cold!!
Ill try that.
I thought it could be if my autogear box is slow to go down in gears, >> the engine stalls.
When I drive, the gear change from 1 to 2 is slow and comes too late. 2 to 3 >> its smooth no more problem.
It could be the oil, not correct as I can't find the original one here....
Any comments are welcome.

[mrfatboy]

While cleaning my desk to do my taxes I found my notes on the WRD thermostat lengths.  I have also corrected my post above to avoid confusion.

Length when cold: ~18mm
Length when hot:~22mm

[Thierry du Laos]

18/22 is what I get.
So what I did is close the air hose and as soon as possible I will see how it goes on the road when hot.
As I wrote earlier, here we are in a tropical country and we don't really need the system to warm up the engine!!!
However, there might be two problems: - The fuel mixture when hot, and the gear box ?
Lets see...

[Thierry du Laos]

Ok, lets update the topic....
Today, I started the engine, but it was hard to start (with the hose blanked) even in our tropical country.
But good surprise, after driving a while, and hot, she isn't stalling like before and even if I think I will raise a little more the idle, I think this test points the problem on the air valve.
So I plan to make sure the valve closes 100% by adding washers in the valve sleeve. Event if it is not opening as much as previously.
I think it should be enough to start, but better driving.
So lets see when I have time to calculate the thickness of the washers, and work this out?
Lets see next step.

[Ulf]

I'm having the exact same issue - I took out the WRD, cleaned it ( a lot of gunky debris came out) and let it soak in WD40, checked the movement of the pin (about 6 mm as mentioned earlier), put it back in and let the car heat up to running temp. Unfortunately it didn't change anything as the car stalled completely when reaching 80 degrees C. So I'll be watching this thread just as much as you :-)

Good luck :-)

Ulf

[Tom in seattle]

I have experienced the warm stall issue.  I finally traced the problem to a defective and severely decomposed fuel filter.  It literally fell apart inside the canister. I cleaned up the canister and inserted a new filter and all is well.  I can't begin to explain why it would start and run well when cold.

[Thierry du Laos]

Update,
I have added 2 mm in the air valve on the injection pump, it is ok now, for cold and warm engine.
Just someting I found too, is that my constant speed actuator is a little slow, or not strong enough to accelerate the engine when going to D or R. Even changing the spring position on the pedal lever to the closer position from the axle. So I changed for a smaller one. Now it is far better....
Getting better and better!!!
Now working on the windscreen washer pump. I saved the plastic pump, but need to re-install the hose to the jet....
But that is an other topic!!