All, I recently acquired my fathers 1999 SL500 with 49,500 miles. The car was bought and driven in Arizona till I had it shipped to Pennsylvania last month. The car overall is in great shape; except for the transmission. The transmission when cold will hesitate and "thunk" when engaged in drive, andwill notadvance pastfirst gear! When the car is thoroughly warmed-up the transmission will perform as intended. I recently took it to my nearest MB dealer whothought the transmissions valve body was at fault and replaced it and performed the recommended transmission service. Unfortunately this did not solve the problem...the transmission will not advance past first gear when cold. It will engage in park, neutral and reverse but not D2, D3, D4 or D5. Any ideas? Thanks in advance for any suggestions.

 

My 1994 SL600 does sort of the same thing. When it is stone cold, it will shift to second gear only after revving the engine to almost 3000 rpm. Once it gets that shift out of the way, then it behaves normally.I hate hearing my stone cold engine rev that high.Also, when shifting from park to reverse or second, it clunks pretty strong when engaging. That too goes away once I drive it and get a little heat in the transmission. I am not worried about that clunk.

I changed my cold driving style a little to get around the delayed first to second shifting problem.I warm up the transmission fluid a little before I drive my cold car.New Procedure: I crank my car up, and then after a few seconds I go ahead and shift it into gear, and then just sit there with my foot on the brake. The fluid warms up as it gets churned in the torque converter which connects the engine to the transmission. If I am patient enough to let it sit in gear and warm like that for two minutes, then it will shift from first to second much sooner.

 

Speedturn, thanks for the reply. Again when the outside temperature was down in the 30's the transmission refused to up-shift (after 10 minutes of driving around in first gear!), but after it sat for over an hour the transmission performed great.It is backto the MB dealer for another try.This time the focus will be on the transmission software/electonics which govern the cold transmission mode. I understand the computer will keep the vehicle in first gear longer to warm-up the catalytic converters quicker for cleaner emissions (asSpeedturn mentioned up to 3,000 rpm). Hopefully this problem will be solved...any ideas?

 

Problem found and solved...the car should have never left Arizona! When cold (below 40 degress) the computer would receive mixed messages from the transmission and as a result keep the car in limp home mode. The solution was to replace the entire shift mechanism because the electronic switches are not individually replaceable. The transmission now shifts as expected when cold. So becareful when you relocate a car from the southwest...they maybethin blooded!

 

Strange indeed, cgsport. I have a 98 SL500 w/77k and have no issues at all with the trans. We had a bout of 20-25F weather when I last drove the car, and everything worked fine. Prior to that the weather was in the mid 40s. You mentioned having the shift mechanism replaced, I wonder if the oil temp sensor is part of that assembly and was itself not sending the correct signals to the ECU/TCM

 

The transmission shifts late when cold to warm up the cats...there is no problem.