Turbo problem on my ML

[asana-wear]

Can anyone help.

I have been told I have a noisy bearing on my turbo. It sounds like a low whistle on tickover and when the engine revs to about 2200 rpm it then goes away. You can hear the usual higher pitched turbo whistle as well. It does not seem to effect performance.

I took it to my local Mercedes specialist (who are excellent by the way) who said a replacement would set me back around £700.

Can anyone suggest another solution such as repair or refurb unit.

The noise is starting to do my head in!!

 

[jgevers]

Yes turbo bearing failure is common (About £450 exchange from MB). Pop the inlet hose of and see if there is any radial and axial ply on the shaft.

But also check the exhaust manifold. They are prone to warping, pulling out the front two studs. They tend to make a shrieking noise when boost comes in for a few seconds. When it gets really bad the noise is there at idle as well.

Cheers,

Job

 

[asana-wear]

Thanks jgevers

It may well be the inlet manifold, now you've discribed it the sound is a "shreiking" and it comes in "on the boost" but goes away after around 2500rpm. It's also there at idle.

What do you reckon a fix or replacement will cost?

Is it a dealer part?

Many thanks for your help

 

[jgevers]

In the garage we normally 'plane' the exhaust manifold, and drill the head to take Time-Serts. This seems to be strong enough to be a permanent fix even on higher boosting (chipped) cars. Normally takes about 4 to 5 hours to do the whole job.

Cheers,

Job

 

[asana-wear]

Can anyone tell me where the inlet manifold is on an ML? I'd like to check it to see if it is the probelm.

 

[asana-wear]

anyone?

 

[Dieselman]

Jgevers said it was the exhaust manifold.

The manifolds are the cast pipes that join to the cylinder heads. The inlet one is either aluminium or plastic and the exhaust one is cast iron and leads to the turbo and exhaust.

 

[Dieselman]

In the garage we normally 'plane' the exhaust manifold, and drill the head to take Time-Serts. This seems to be strong enough to be a permanent fix even on higher boosting (chipped) cars. Normally takes about 4 to 5 hours to do the whole job.

Cheers,

Job

This makes me wonder if the exhaust has too much back pressure or the EGT has become too hige, say after chipping.

Has anyone measured the EGT?

 

[asana-wear]

Thanks for the reply Dieselman

Don't know, the Guys at Stutgartt garage (a specialist) did a download and had to change the MAF filter But said everything else checked out.

They said the turbo bearing was the problem noise. When jgevars said about the screaching at boost and low pitched whistle at idle, it got me thinking!!!

Another thing it seems noisier in wet weather (although it may well be my imagination!!!)

What is EGT anyway? How would the back pressure effect/cause the noise?

 

[asana-wear]

Anyone know what EGT is and what causes back pressure?

 

[mergli]

EGT is Exhaust Gas Temperature - sorry that's all I know about it

 

[Dieselman]

As said ECT is exhaust gas temperature. If this goes too high, due to the amount of fuel comared to air being too high, then there could be locallised overheating problems.

If the car has been chipped this will increase EGT due to the additional fuelling, likewise a blocked exhaust will restrict the amount of air and cause a similar effect.