Constant rattling noise from my cls

[AllzinoMb]

I have a rattling noise coming from my engine when the car is standstill but running also when i Rev it very slightly... couple mechanics recommended I need my timing change replaced which I was quoted £1.6+ and also my rocker cover gasket is leaking which I wanted to know if this a possible relation between the two. I took it to Mercedes them selves for a investigation which cost £120 an hour and after having the car for 3/4 days they came back and said they need further investigation to open up the engine to check the time chain which they quoted me £540 which I didn’t go ahead with. I wanted to find out do I just go ahead and get the timechain replaced or could it be something else??

 

[brandwooddixon]

Hi welcome, although this post is really in the wrong forum location.

Rocker cover gaskets are a common fail point on some engines, an easy fix and wont be related to any timing chain rattle.
Some engines are known to exhibit "timing chain wear" and stretch as they age more than others due to the design of the chain and tensioner gear.
It's possible to check for a stretched chain on many engines without much disassembly (just removing one cover).
I'd recommend getting a worn chain and gear replaced as its cheaper than a replacement engine which is what you'll be looking at if the chain jumps any teeth on the camshaft gears.

You're certain that the rattle is from the front of the engine? I ask because exhaust heatshields and clamps and auxiliary belt wheels are another source of rattles.

It shouldn't take 3 or 4 days for MB to fix let alone diagnose the issue.

If you're based in the UK we may be able to recommend an independent MB specialist that would be able to give you an honest assessment.

 

[AllzinoMb]

Thank you for response. The noise is from the back side of the engine which is where the chain is placed. I am based in London

 

[brandwooddixon]

Ah, its an OM651. Hmm. I think that you'll be looking to tensioners first as I believe that a chain replacement is possibly an engine out job, this would explain why MB want 3/4 days to fix it although that seems a little excessive still.
Whereabouts in London?
I guess that alexanderfoti (AMF automotive) in Tonbridge might be too far same with Wayne Gates in Harrow.
Best to post in the Engine/Drive train section and ask there.

 

[Uncle Benz]

It’s likely to be the chain. It’s not uncommon, sadly. How many miles are on the engine? The problem isn’t limited to mercedes. I’ve done a BMW with the N47 diesel engine this week. A similar sort of job with the chain at the back. It is possible with the om651 to join a new chain to the old and wind it in, but I’d only suggest that if you were planning to jump ship and trade the car in soon after. A pic of the BMW I fixed this week…