SLK 230 Engine noise

[Richard Mason]

Hi all, just returned home with the the SLK 230 making a whining noice from under the bonnet. Its worst when you accelerate. Seems to be coming from the exhaust side of engine. Could it be supercharger on way out or alternator bearings. Will have to take in for repair but would be pleased if someone can give any ideas as to the problem. 51 reg with 70,000 miles Auto. Thanks for your help.

 

[Adam230K]

how loud?

 

[Richard Mason]

Hi Adam, Noise comes in at about2000 rpm not all that loud, don`t think its supercharger or alternator. Gets increasingly loud as revs increase. Same noise when stationary as being driven. ? could it be torque convertor

 

[Adam230K]

thats the normal behaviour of the supercharger, it has an electromagnetic clutch which engages around 1600-1700rpm and thats why u will hear the whine. When stationary if i floor the pedal and let go i can hear it almost 'meow' like a cat (we have the same engine).

if the performance of your car is fine, then that noise is normal.

 

[Richard Mason]

Adam, thanks for that. Yes that "Meow" is a good description but this noise has only just started last night. Never had a problem before. Thanks for your input. Richard

 

[Adam230K]

When i first bought the car i had to listen very hard to hear the supercharger, but now i can hear it alot more, it might be a sign that you are getting used to the car. I wouldn't worry too much!

 

[Bobby Dazzler]

We have a meow in the ML - I described it as a meow too. We suddenly noticed it some time after getting the car, but I think it was there all along. I concluded that it's the wastegate releasing boost pressue.

A meow would imply that it's a short noise though, a while would imply longer. Is it a short noise?

 

[Adam230K]

I only describe the 'meow' that i get when quickly depressing and releasing the accelerator to confirm that Richard's engine does the same thing that mine does.

When i'm flooring it in low gears i can hear a faint whine, if i'm in 1st or 2nd the whine is much more audible and upon changing gear it lets off a very audible 'meow' sound which i also think is the wastegate.

 

[Richard Mason]

Will pass on you comments to the garage in the hope that they can solve this. On reflection think it sounds more like a circular saw cutting wood. Can`t leave this will have to get the garage to investigate more.
Thanks once again you are all very knowlegable on this site.

 

[Will]

I bet it's the idler tensioner wheel on the poly V-belt.

I had the exact same symptoms on a M111 230K engined W202 at the same sort of age/mileage a few years back.

It's a small plastic pulley/wheel with a bearing in the middle that the V-belt runs on. The bearings dry out and fail creating the noise, and one of these sits on the exhaust side of your engine.

You could *carefully* stall the wheel or remove it to check for yourself. I think the part is about £20.00 from the main dealer.

HTH

Will

 

[Richard Mason]

Hi Will..away yesterday but just looked at your suggestion. Thanks very much will check that out . I think that could be the problem. Will reply when I get to know some more. I am very hopefull. Cheers Richard

 

[phil c]

Hi all Richards car is now sorted , it had the dredded anti freeze inside the gearbox , and lots of shrapnell in the sump , we fitted a new box , torque coverter and radiator and its now sorted .