Whining noise from M113 engine (2004 C209 CLK500)

jeremy156

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Hi folks, wonder whether anyone with a good ear can identify from a video what's making a whining noise at the front of my engine? It's pretty loud from inside the car, rev dependent and I assume it's the alternator... but grateful for any insight.


Thanks,
Jeremy
 

LostKiwi

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Drop the serpentine belt off (take note how it went!) then rotate each pulley by hand. One or more will feel wrong (rough, sloppy, loose) and that will be the culprit.
 
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jeremy156

jeremy156

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MBS is my second home - I like to try and have a go myself first and then at least take it in with “I’ve tried X, Y, Z” :)

Thanks Alastair, I’ll give that a try tomorrow - feeling brave.
 
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jeremy156

jeremy156

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Hundreds of really bad YouTube instructional videos out there, but found a really good one where they’ve taken the time to prepare and make it all visible, removes some of the guesswork and obscurity :)

 

rifiki

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Alternator? Have had alternator whine so loud to be almost defending, new bearings.
 

Terrykal

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I have a whining noise coming from engine, checked with neutral & parking in gearbox too so its not from there.
i was thinking it is coming from idler pulley, I ordered a gates poly v kit but when removed the belt, only the idler was producing noise. I replaced only this pulley and the belt and the whining noise is still there.
all other ones are quiet and can rotate freely with my hand (apart from crank apparently) and there was just a slight noise coming from the a/c. Is it replaceable?
Generally speaking, can one replace all the pulleys i.e. of the steering pump or coolant? or you have to replace the complete pump? also, what is the life expectancy of the coolant pump? my car has now 85k miles.

I am uploading a belt graph for M112-M113 engines for future reference. I found it at autozone and just used some colouring for an easier identification.
 

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LostKiwi

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'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
I have a whining noise coming from engine, checked with neutral & parking in gearbox too so its not from there.
i was thinking it is coming from idler pulley, I ordered a gates poly v kit but when removed the belt, only the idler was producing noise. I replaced only this pulley and the belt and the whining noise is still there.
all other ones are quiet and can rotate freely with my hand (apart from crank apparently) and there was just a slight noise coming from the a/c. Is it replaceable?
Generally speaking, can one replace all the pulleys i.e. of the steering pump or coolant? or you have to replace the complete pump? also, what is the life expectancy of the coolant pump? my car has now 85k miles.

I am uploading a belt graph for M112-M113 engines for future reference. I found it at autozone and just used some colouring for an easier identification.
You can't (easily) replace any pulleys other than the idler and tensioner.
If the alternator is noisy the bearing is integral to the alternator, same with power steering pump and water pump. Depending on the AC compressor you may be able to replace the pulley and clutch assembly but they rarely make noise and when they do (assuming a clutched compressor) only when the clutch is disengaged. If it's a non clutched compressor the bearing are integral to the pump.
 

Terrykal

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LostKiwi thank you for your reply. so steering & water pump is a complete pump replacement.
alternator pulley is very quiet at the moment and when I searched online for an alt's pulley replacement I figured out that does not have bearings (I was not sure for that and I raised a question in another post in this forum).
I know from my previous bimmers that the new japan made a/c compressors are variable compression so they do not have a clutch but a valve that will close the system to start compressing the gas.
I will have a look online to see what type is on my CLS, if not mistaken its a Denso one and it has a clutch.
 


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