Engine / transmission noise help

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New Member
Aug 31, 2018
C Class
Hi All,

Please could someone kindly listen to this engine noise to help me work out where it’s coming from or what it is..

I have uploaded to YouTube:

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Here is some background info:

- Mercedes C Class 250 - 64 plate. (W205)

65000 miles.

- issue only occurs high gear (5th) and low RPM 2k < (where tractoring would usually happen in manual gearboxes).

- usually happens when the automatic gearbox trips from 4th to 5th, and the RPM drops (on video the noise occurs when gear changes from 4th to 5th).

- only happens when pulling (I.e driving up hill, or accelerating, when taking foot off acceleration, noise goes away).

- doesn’t happen when in sports / sports plus mode due to higher RPM before gear change (noise only occurs low RPM 2k < and high gear 5 >)

- doesn’t happen when coasting.

- doesn’t happen when revving engine in neutral even to red line.

Finally, I noticed the noise a few weeks after taking for a massive service at my local Mercedes SPECIALIST garage (not dealership) where they performed a gearbox oil and filter change.

It’s the first service of this kind due to mileage and age.

I have spoke to garage on phone and they want me to take it back down on Friday to check their work, but they did said it was a routine gearbox oil change and they use a computer / software to conduct the oil change, plus genuine parts and oil used to preform the gearbox / transmission service.

I know they did use Mercedes oil and parts as I saw the delivery or parts when dropping off for service.

I don’t want to go in on Friday and accuse them of not doing the service correctly, but does anyone have any idea what could be causing the noise? Maybe not enough gear box oil, or a loose panel / part?

Just incase you can’t hear on the video... the noise is like a clicking / motor / vibrating noise. Only lasts a few seconds at a low RPM in high gear, goes away if manually dropping the gear back to 4th using flappy paddle or when the RPM increases.

Any help would be much appreciated.

kind regards,
very difficult to tell, sometimes noises can have you running round chasing unicorns and you never find out the cause, If they have removed any covers or heat shields it could be one of those vibrating. Is the noise inside the car or coming from the out side, front or back? I have never heard anything like it before, but probably worth just getting it checked out.
Hi Tony,

Thanks for reply.

Strange noise indeed, just hope It doesn’t lead to anything expensive. I’m hoping your right and it’s a loose panel or heat shiel

The noise seems to be coming from engine bay.. or around that area.

If they have not put enough gearbox oil in, could this sound similar?

Thank you,
Hopefully its nothing much, on my S204 the plastic engine covers and pipes vibrate like crazy, terrible design, I would junk the things, why they need to cover engines in plastic is beyond me.
If I remove the engine covers mine is soo much quieter..

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