SOLVED - Engine rattle on startup, timing chain rattle on low rpm driving
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Bertie_
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May 8, 2026
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Might try this mod, since it fixed the startup rattle for you.
You still haven't replaced chain tensioners and installed check valve, right?
Another suggestion I got from a retired Mercedes mechanic was to try thicker motor oil.
Correct, I have not done the TSB. I am still thinking about doing it. I am running the thicker spec AMSOIL 5W-40 FS Originally Posted by gbm
I have a C350 2013 (M276) with startup rattle as well, and my engine also falls under the "replace chain tensioner and install check valve" category.Might try this mod, since it fixed the startup rattle for you.
You still haven't replaced chain tensioners and installed check valve, right?
Another suggestion I got from a retired Mercedes mechanic was to try thicker motor oil.
Unfortunately the warm-startup rattle is due to the tensioners losing pressure and needed 1 or 2 seconds to pressurize again.
Does thicker oil help reduce noise ? What oil? A mechanic recommended I try a 1/2 qt of Lucas just to see if noise is reduced , I still have not checked pressure my noise is all the time now .
John CC
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The idea is it helps reduce the leakback so the tensioner (or lifter, etc) isn't as empty on the next start.Originally Posted by Mmr1
Does thicker oil help reduce noise ?
Quote:
Unfortunately the warm-startup rattle is due to the tensioners losing pressure and needed 1 or 2 seconds to pressurize again.
Originally Posted by Bertie_
Correct, I have not done the TSB. I am still thinking about doing it. I am running the thicker spec AMSOIL 5W-40 FS Unfortunately the warm-startup rattle is due to the tensioners losing pressure and needed 1 or 2 seconds to pressurize again.
Switched to 5w40 yesterday (from 5w30), let's see how it does. It does feel different when driving.
From what I've read it might be the tensioners, or it could be something with the camshaft adjusters that cause rattle.
Local mechanics told me it's the timing chain that might be worn.
Retired Mercedes mechanic was certain it could not be the chain in any case, said it could be the tensioners.
Car has 172.000 km on the clock.
My startup rattle is on
- cold startups
- warm start, after it has been off for 15-30 min
& always goes away after 2-3 seconds.
It does not rattle when just turned off and turned on again in less than 15-30 mins after turning it off.
