ML 350CDI engine noise when hot ?

ML 350CDI engine noise when hot ?

Author
Discussion

MatrixXXx

Original Poster:

653 posts

159 months

Tuesday 26th February 2019
quotequote all
Hi, I have had my ML 350CDI 2011 for a few months now , and cant trace the source of noise from the diesel engine when warm/hot.
the sound is like a bike chain bieing draged across a plastic surface , not at the same revs as the engine, and only when light throttle, and between 1800-2300rpm.

when the engine is cold it is quiet , no chain rattle etc, and has so much more torqe than when warm/hot.

I have changed all the pulley tensioners and alternator freewheel pully, which made it a bit quieter but not got rid of the noise, I have changed the charge air seals either side of the turbo noise attenuator, which seems to give more torque. I can see oil weeping from the pipes into the intercooler, I assume if oil can get out so can the presurised air?

or is the OM642 engine just very noisy?

I normaly go for big V8 petrol engines which sound so nice.

om642 engine, 74k miles.

foz01

771 posts

270 months

Tuesday 26th February 2019
quotequote all
Oil weeping out would indicate turbo seals?

MatrixXXx

Original Poster:

653 posts

159 months

Tuesday 26th February 2019
quotequote all
Changed 2 of the 3 seals made no difference.

Paddymcc

1,011 posts

198 months

Tuesday 26th February 2019
quotequote all
MatrixXXx said:
Hi, I have had my ML 350CDI 2011 for a few months now , and cant trace the source of noise from the diesel engine when warm/hot.
the sound is like a bike chain bieing draged across a plastic surface , not at the same revs as the engine, and only when light throttle, and between 1800-2300rpm.

when the engine is cold it is quiet , no chain rattle etc, and has so much more torqe than when warm/hot.

I have changed all the pulley tensioners and alternator freewheel pully, which made it a bit quieter but not got rid of the noise, I have changed the charge air seals either side of the turbo noise attenuator, which seems to give more torque. I can see oil weeping from the pipes into the intercooler, I assume if oil can get out so can the presurised air?

or is the OM642 engine just very noisy?

I normaly go for big V8 petrol engines which sound so nice.

om642 engine, 74k miles.
Isn't there some sort of a noise restriction thing in around the pipework to the intercooler around the front of the engine? Might be worth a look there if oils leaking somewhere the air will definitely be leaking too.

MatrixXXx

Original Poster:

653 posts

159 months

Tuesday 26th February 2019
quotequote all
You mean the turbo resonator , it is ok and I replaced the seals either side.

Gsekke

1 posts

28 months

Friday 22nd July 2022
quotequote all
Hi

I have a similar issue on my G wagen 350 CDI. Did you identify the issue on your engine?

MatrixXXx

Original Poster:

653 posts

159 months

Friday 22nd July 2022
quotequote all
No I ended up selling it, lost quite a bit on it , my last Mercedes.