UK Car Repair Questions? Ask a Mechanic for Answers ASAP
Hi, the first thing you should do is make sure that the transmission fluid is at the correct level using the Mercedes dipstick tool. A whining sound from the transmission is usually an indication of low fluid or a plugged filter or a bad pump assembly. If the noise is back after the filter change I'd suspect a pump problem. If the noise is gone but the transmission still won't shift you can try replacing the conductor plate in the transmission. If you continue to have trouble you will likely need to replace the transmission. On the early E class models there was also a problem with coolant mixing with the transmission fluid and ruining the transmission. You should have the fluid analyzed for coolant contamination. If there is coolant in the fluid you will also need to replace the radiator. A diagnostic scan with the Mercedes Star Diagnosis tester may reveal fault codes for the speed sensors in the transmission. If that is the case I would replace the conductor plate.
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