Terrible engine/gearbox whine W202

[deegee]

My first Mercedes ownership--1999 W202 C240 V6. Extremely impressed with build quality ( I have driven Audi's for over 20 years and thought nothing could compare--I was wrong!!). The V6 engine is very smooth with impressive
pick-up when required. I have only two criticisms 1. Fuel consumption is about 24 mpg (perhaps I am being greedy as my right foot is pretty heavy)and 2. Since I have had the car (2 months) there has been a high pitched whine audable at all engine speeds but louder under acceleration. My local indie insists this is normal with the M112 V6 but I cannot imagine that if I had bought thiis car new and handed over nearly £30,000 I would have accepted the terrible whine. I would be very grateful if any M112 V6 engined drivers would let me have their views--I suspect an alternator bearing (it is that type of noise.

 

[anyweb]

any chance you could record the audio of this 'whine' ?

 

[deegee]

Sorry anyweb, thanks for replying. I wouldn't know where to start!

 

[television]

Is the whine when you are pulling, and goes on the over run (foot off)

 

[mebobster]

hi, i am not an M112 V6 engined driver, but a friend is, his problem was water pump & belt, may sound stupid, but worth a try. alternator bearing also sounds good to me.

 

[deegee]

t
television-the whine goes when foot lifted,
mebobster-thanks I will try water pump if not alternator bearing.

 

[jibcl500]

Take the belt off and start the car see if the noise goes.

jib

 

[deegee]

jib-thanks. I will try removing belt tomorrow. If the whine goes I can rule out
water pump & alternator bearings??

 

[deegee]

Sorry, I meant if the noise stays!!

 

[jibcl500]

if you spin the pully on the alternator it should be silent,

jib

 

[deegee]

Many thanks jib.

 

[oigle]

If the noise disappears on over-run or when foot off the accelerator, I doubt that any of the belts, alternator, water pump suggestions are correct. I would be more inclined to look at the transmission for the cause - gear/bearing noise etc. You didn't say if auto or manual gearbox, but both can whine. Differential too, for that matter but you should be able to tell where in the car the noise is coming from and work from there.

 

[deegee]

Thanks oigle, the car is going in for an ATF and filter change on Thursday which might prove interesting if it is a gearbox problem. Bearing in mind that I was told by my indie that the noise is normal with this engine I would still like aC240 owner to let me know if it usual or not!.

 

[alancee]

btdi

i respect everyones views but been there done it with my e240 ,same engine i think 2.6,could be 2.4 ,normal noise dont think so ,i changed my diff and it is silent now ,diffs do wear ,i posted pictures of my duff diff here,not a big job ,couple of hours on a lift,but do get same ratio as you have otherwise you WILL NOT get all your gears ,presume auto not read it all,i have a diff and there are loads on ebay,you could change your diff for less than the cost of an auto oil change

 

[deegee]

Thanks alancee. Iam going through all the other possibilities first eg. bearings affected by the belt plus I am having the atf and filter changed today. If none of this helps i will investigate the diff--thanks again for your help.