Mercedes ML 350 CDI Engine noise

[Matrixx]

Just thought i would ask if anyone who owns an ML diesel has had any issues with odd engine noise.

the noise is like someone dragging a chain over and alumimiun/plasitc surface, it matched the engine speed but at a different speed ie aux belt , 1200-1400revs.
i have changed all the pulleys, and alternator drive pully, changed various charge air seals, changed the oil, the engine is silent when cold ( which rules out a loose timing chain), and only makes the noise when at operation temp and on light acceleration.
so at motorway speeds it constant on slight inclines. my wife thinks it is just the noise a diesel makes?
I normally buy big V8's so have never had this problem.

om642/ w164

 

[Ruffian]

Is this the ml with the viscous fan same as the Vito??
As had a really weird chatter from the fan shroud at the bottom the radiator before being too loose.
A bit or rubber pipe or a cable tie to take the slack up and a weird noise disappeared.

 

[mr haynes]

Oil thins as it gets warmer so wouldn't rule out timing components. Are you sure not gearbox related? Is noise present at idle?

Good call on rubbing. Pop bonnet and listen/poke around for anything loose

 

[Matrixx]

Oil thins as it gets warmer so wouldn't rule out timing components. Are you sure not gearbox related? Is noise present at idle?

Good call on rubbing. Pop bonnet and listen/poke around for anything loose

no noise at idle, checked all over for losse hoses, etc, nothing, I suspected the transfer box but found it was in the middle on the ML, could be transmission, but that would be prety major, could be a drive shaft bearing, thought it might be cavitation in the power sterring pump, there must be other people with the same noise as these enginesa are in quite a few vehicles.

I have heard the noise in a petrol jeep I had on hard acceleration, which would point to transmission, but they are difficult to pinpoint.

 

[mr haynes]

Tends to point to transmission, could be shaft bearing on the turn

 

[Lazurus]

Hmmmm sounds expensive what ever it is