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Mike, Technician
Category: Mercedes
Satisfied Customers: 39198
Experience:  34 years of in the Motor Trade as diagnostic Technician and general repair work.
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Mercedes-Benz ML350: 2011 ML350 4MATIC, I have a loud whining

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2011 ML350 4MATIC, I have a loud whining noise coming from the engine/powertrain. The whine is consistant with engine speed, only heard in the lower gears(1-3), and does not go away. I have been to the dealer and they have replaced the a/c compressor and the power steering pump. We even took a drive in a few other similar ML and they all had the noise to varying degrees, so now they are saying it must be normal. Help!
Hello and Welcome to justanswer..

My name is XXXXX XXXXX Im happy to help you ..

With this sort of an issue, a good way to trace down such noises is to remove the belts and run the engine just briefly, then see if the noise has gone - if it has, then you know it is one of the driven pulleys at fault.

You can then check each individual pulley for play etc -manually feeling / rotating - tugging at the pulley wheels to reveal any issues and the same with AC compressor pulley unit - -and that usually will if there is a fault there.. and then you can progress to a fix there.

If no such issues are found, then fit another, new belt - Sometimes its the belt that has hardened and is causing the noise- and that sorts it.

If the noise does not abate with the belt off - then the fault is either in the engine or the transmission - which would need further/ deeper investigation....

BUt thats the way to go through it. Its time consuming so I suspect the dealer does not really want to get into that - but that would be the way. You will have to put this to the dealer thats looking at it for you -

Best Rgds --- MIKE.

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You can get back to me anytime you might need too after that - you are always welcome.

Rgds - MIKE...


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Customer: replied 3 years ago.

Thanks Mike.