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MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4317
Experience:  Mercedes Benz Qualified Diagnostic Technician
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Car is a Mercedes benz ML270 CDI year 2002. Idles ok between

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Car is a Mercedes benz ML270 CDI year 2002. Idles ok between 700-800 rpm when in neutral or park, but when i press the brake and hold it the shifts to drive the whole car start shaking. RPM decreases by about 600-650 rpm or so. No dtc in ETC or Engine. Took off the drive belt an ran the engine same result. what could be causing this problem.
Hi,This sounds very much like a bad torque converter - it can be very difficult to say for sure as being a mechanical fault it will show no codes & there are no real tests you can do other than the feeling it gives from experience so would recommend someone that knows Mercedes testing it but if the revs drop right down to the point where it feels like it will stall the engine (or it does actually stall) then I would say that the TC is not providing enough slip - I have seen this quite a few times. You could try having a transmission flush & oil & filter change - this can help with a sticking TC but is by no means a definate fix & may require a new Torque Converter to cure the problem. Also do check all engine/transmission mounts as this can cause the whole engine to judder however would not explain the drop in engine revs. Best regards, Paul
Customer: replied 6 years ago.

Did the trans oil and filter change but the situation remain unchanged. So the torque converter is the must likely culprit.

Hi - yes, I would say so based on what you have said but would recommend a mechanic that knows Mercedes confirm first by experiencing the problemBest regards, Paul
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