It got very cold during the past several weeks (as low as - 25 C at night). My '90 300 SL started without any problem. However, shortly after the car warmed up (operating at 80 C), it continually stalled when I came to a stop. It would re-start without any problem after I open up the throttle a little more. This happened 6 or 7 times while I drove my car to the MB dealer. When I got to the service dept., it was fine. Because it was so cold, I did not use any of the electrical extras (e.g. seat warmers, defogger, etc.) when this problem occured. I also use synthetic oil. The car has 180,000 km. It was recently tested for emissions and compresssion tested and passed by flying colors.

The dealer service dept. ran the usual tests and did not find any problem. They could not duplicate the problem. They did, however, noted that the engine coolant temp. sensor was leaking slightly and MAY be the problem but they were not sure. In any event, this sensor was replaced.

It is now not as cold and therefore I have not experienced this stalling problem anymnore. However, I am concerned that the MB service dept. cannot diagnose the problem and therefore I am hesitant in taking this car for any kind of long trip until I am comfortable that the problem is solved and not just waiting to re-occur.

Any suggestions as to where to direct the MB tech. to look?

Many times the problem isn't even viewed by the fuel computer. Over voltage relays, & crank position sensors can cause this problem & both are hard to diagnose. The 1990 SL didn't have very smart computers so don't give up yet. I'd start w/overvoltage relay as they don't last forever. 300SL's also had coil problems & that won't show up either.

I had a 1990 300E with similar problem. However, I live in southern California and it did not appear to be related to weather. At about 80,000 miles the car would stall intermittently when the car is stopped at a light or slowing down. The car would then start right away and would be fine. The car seem to stall right before the car come to a stop. This would happen probably one out of every 10 stops. Of course, this would never happen when the dealer test drive the car.

After about 2 months in the shop, with almost every sensor and valve replaced, the dealer found the problem with a "speed sensor in the dash board". I am not sure of the exact technical term of the speed sensor. They replaced the relatively inexpensive part and the problem resolved. I hope this is helpful.

BTW, I also had to replace my coolent sensor about the same time. It was corroded and leaking. The coolent light would come on and off at times. While you are at it, check out the neck of the radiator pipe. Again, I am not sure of the technical term. The pipe on the right side of the radiator that the hose is attached to. Apparently, the neck on my car got corroded and it blew my hose off one day.

[This message has been edited by CC (edited 02-07-2000).]

Thanks M.B. Doc. I just had the dealer check the over-voltage relay and the coils. They could not find anything wrong here either. I am going to leave this problem for the time being. Maybe it was the coolant temp sensor that was replaced. It is just frustrating that this problem cannot be identified before so that I can aviod the risk of possibly being stranded. The next time I bring my car in for service, I will have them look at the speed sensor also if there is such a device in my car.

P.S. The hose connector on my rad already blew. I had it replaced a year ago.

Thanks everyone for your suggestions.

Chaudo,

I got my invoice out and this is what they did to fix the stalling problem:

Test and replace vehicle speed sensor behind speedo, replace fuel mixture pin, leaking injecton switch.

Good Luck!