Why Is My Ml 270 Is Whistling!!!!!!!

[cliffclop]

Hello everyone,
I'm after some advice please. Usually when cold when I pull off and it goes through the gears as I put my foot down to go out of the hills where I live, a loud tweeting (like a loose fan belt) can be heard. It's only when she's in gear and pulling. Is it the fan belt or some other belt under there? Or something more sinister? Anybody know, please? Cheers. Cliff

 

[BlackC55]

It is possibly the turbo spooling up?

 

[verytalldave]

Is this noise ONLY whens its cold?

 

[cliffclop]

Yes. Noisier when very cold and gets less as engine warms up. in neutral no noise.

 

[verytalldave]

I posted a similar question about a month ago. Apparently it comes from the auto gearbox. Once it gets up to proper working temeperature the noise stops.
I described the noise as "a turbine-like whine". Several answered saying this was normal and should stop once warmed up - which mine does. If the noise continues while hot, then get the level of the auto fluid checked.

 

[JEZ.S320L]

I posted a similar question about a month ago. Apparently it comes from the auto gearbox. Once it gets up to proper working temeperature the noise stops.
I described the noise as "a turbine-like whine". Several answered saying this was normal and should stop once warmed up - which mine does. If the noise continues while hot, then get the level of the auto fluid checked.

Yes, mine is exactly the same. I have been assured by MB, that it is normal.

 

[cliffclop]

So what you reckon, leave it and relax?

 

[JEZ.S320L]

So what you reckon, leave it and relax?

Yes - relax

 

[Dosco]

Just hope it is not a Canary!

 

[cobra]

noise

i also have ml270 with same noise is it possible this noise could be caused by the engine mounts being more solid when colder transmitting noise (seem to remember reading somewhere that mounts are oil filled) then as they move and create friction and pliability, warm up and reduce noise, basicly would changing mounts cure it
thanks cobra

 

[oigle]

It is possibly the turbo spooling up?

I totally agree. Extra rich mixture when cold causes turbo to whistle under load when cold. As it warms, the mixture leans out and whistle gradually disappears. It is even more noticeable with a chipped motor as mixture is a bit richer again. Various engine oil viscosities seem to vary it too. Heavier oil - more noise. The noise is very identifiable as a turbo whistle to those who know that particular sound.

 

[verytalldave]

Bearing in mind my car is fitted with a compressor (supercharger) and not a turbo, I expect the same could be said for both devices.

 

[oigle]

That came out of left field, didn't it!!! How come? Did you remove the turbo and install a supercharger? If so, why??

 

[oigle]

OOps!! Didn't look. Thought you were the originator of the thread!! Sorry. I think supercharger whines are in a totally different category but have little experience with them. I know they normally are quite noisy by comparison.

 

[cliffclop]

what is meant by turbo spooling up? Does it mean the turbo is on the way out?

 

[oigle]

what is meant by turbo spooling up? Does it mean the turbo is on the way out?

Not at all. Just a term used to describe the "speeding up" of the turbine when sufficient exhaust gas passes through it. They rev over 100,000 rpm at full chat. Heat and cleanliness are paramount issues with these little beasts.
If you don't hear some turbo whistle occasionally, particularly when cold, often means they are not spooling up properly due to any number of factors. A crook maf, for instance will prevent them spooling up, and thus no boost.