BenzWorld Junior Member
Date registered: Jun 2018
Vehicle: 2003 C240 4Matic sedan
Location: Raleigh, NC
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
I just went through something similar on a 2003 C240 4matic. No codes, no limp mode, when the car was cold from sitting overnight I could start the car and it would move in forward and reverse for a minute or two, then the whine of the pump would become apparent and the transmission would no longer engage any gear. I opened the cooling line at the radiator, while the engine was running and found no flow. Transmission fluid level was reading too high and the level didn't change after engine start which told me the pump wasn't pumping.
The whine of the pump was telling me the pump is running but starving for fluid. I had recently changed the transmission fluid because of anti-freeze contamination. I had also installed a new conductor plate and new transmission filter. I had then put about 500 miles on the car when this problem cropped up. Since the filter was new, I had discounted it as a problem.
Bottom line was I installed another new transmission filter and now the pump whine is gone and the car is back on the road. In my situation I should have flushed more transmission fluid through the system to remove as much crud as possible. I had dropped the pan several times and was not finding any sediment that would clue me in to a clogged filter.
It's an inexpensive thing to try before taking more drastic measures.