- 2007 R320 Diesel OM642:
- 2 sec. thrashing sound at startup on Cold Start and in Cold Idle
- You can hear a short 2 sec. thrashing sound at startup (on passenger side) that seems to go away as the OM642 warms up.
Diagnosis: suspect: Timing Chain Tensioner may need replacing.
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Timing Chain Tensioner:
http://www.mbpartsworld.com/images/p...186.070426.jpg
(Items 65)
Reference #'s: 642 050 03 11 & 68017937AA
http://ecx.images-amazon.com/images/...CL._SS270_.jpg
Question: Does this Diagnosis sound correct?
Question: Where is the Tensioner on the outside of the motor and is it reachable?
Question: Has anyone come across a right up on this Tensioner replacement? I've looked everywhere, Sprinter/Chrysler/Merc forums ...
Junior Member
It is not the tensioner, it is the chain. You have to have the chain and tensioner replaced by a mechanic who has done this before. This is perhaps the most common and famous problem that the OM642 has. There are many aftermarket kits available much cheaper than OEM. I used one and so far it is good. Google it. Roger
Newbie
Well my R320 170K miles started to rattle more and more annoyingly so I changed the timing chain tensioner and the noise appears to have gone away.
I knew it was the timing chain/tensioner as I removed the oil filler cap - ignored the oil splash and with a torch I could see the chain wobble (and tensioner wobble) coincide with the noise. Note a glass spy oil cap (if one exists) would be a useful diagnostics tool in this case to save you from oil splash.
Replacing the tensioner on an R320 is more difficult than Alex's ML video - there is no access - only from above. You need strong hands and there is a knack in that you want to pull the tensioner a little upwards as you push it in and turn. Note I removed the cabling around the tensioner as best as I could and I levered the timing chain using a bar through the oil filler cap to help reduce the force necessary to insert the tensioner. I feel I got lucky as I was struggling inserting the tensioner against the force of the spring and turning at the same time - and doing my best to hold it in so that there was no risk of stripping or damaging the top thread.
I knew it was the timing chain/tensioner as I removed the oil filler cap - ignored the oil splash and with a torch I could see the chain wobble (and tensioner wobble) coincide with the noise. Note a glass spy oil cap (if one exists) would be a useful diagnostics tool in this case to save you from oil splash.
Replacing the tensioner on an R320 is more difficult than Alex's ML video - there is no access - only from above. You need strong hands and there is a knack in that you want to pull the tensioner a little upwards as you push it in and turn. Note I removed the cabling around the tensioner as best as I could and I levered the timing chain using a bar through the oil filler cap to help reduce the force necessary to insert the tensioner. I feel I got lucky as I was struggling inserting the tensioner against the force of the spring and turning at the same time - and doing my best to hold it in so that there was no risk of stripping or damaging the top thread.
