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Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 22758
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 2008 RHD 200 CDI Sport. 68000 Miles. Initially the

Customer Question

I have a 2008 RHD B 200 CDI Sport. 68000 Miles. Initially the problem was the 'engine' was noisy from start up, when the ambient temperature was low. It went away as soon as the engine warmed up or when the revs exceeded 900rpm. Now it is noisy on start up, even in warm weather, however the the noise only occurs when the engine is idling and disappears above 900 rpm. Although I refer to it as 'engine' noise I personally believe it is outside of the engine block. The sound is coming from an area below the battery box on the drivers side of the car. It is so bad that when I am stationary it attracts the attention on passers by.
Very embarrassing from a Mercedes.
Submitted: 7 months ago.
Category: Mercedes
Expert:  victoria-mod replied 7 months ago.
I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.
I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.
Thank you!
Customer: replied 7 months ago.
I have to say, Victoria, I am not altogether surprised. Let's give it 24 more hours then if I haven't had a response, I would like my money refunded. Thanks David.
Expert:  Matt replied 7 months ago.


sorry about the wait

can you describe the noise for me ?

is its a regular tapping that increases in tempo with engine speed?

if so then it could be a sticking valve lifter, as these use a small hydraulic piston to take up the valve clearances and what can happen is the small oil ways that feed the piston chamber can get clogged up

So the 1st course of action is to try an oil flush treatment complete with a new filter and fresh oil

if you don't think this is it then try removing the auxiliary drive belt and turning every pulley and ancillary ( power steering pump , alternator etc) by hand. All should turn easily (with the exception of the AC pump) with no grittyness or wobbly pulleys- If you do find a sticky pump / alternator then it should be replaced or repaired
If the engine is stone cold you can briefly run it with no belts to see if the noise changes or has gone away, this will help show if an ancillary is the issue

Expert:  Matt replied 7 months ago.

do you still need help?
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