I'm pretty familiar with the common causes of engine noise and vibration in the 617 engine. As a new owner of an SDL with the 603, though, I'm still getting used to the differences in noises that it makes. Mine seems to have a slight vibration noise; not necessarily at idle, but if you give it a little bit of throttle, and then it seems louder than I think it should be as the RPMs climb while driving. I'm not talking about the engine itself vibrating the car (the engine mounts were just replaced a few weeks ago), but rather a vibration/rattle like sound that gets louder as the RPMs increase. It's something I can hear, not something that I can feel.

The 617 has well known issues with the air cleaner mounting bracket. I've replaced mine several times. But the 603 has a completely different air cleaner setup, and it seems better isolated from the engine itself.

I was thinking that maybe it was the underbody engine "encapsulation" panels vibrating (mine are in place), but I'm not sure. Are there any other areas that are common causes of noise? I'm thinking it's something in the engine compartment that vibrates when the RPMs increase. I can hear a ticking noise at idle that I assume is associated with the lifters or injectors, however that's unrelated. I haven't done a diesel purge yet and am not really concerned about the ticking, based on what I've read on the forum.

Any thoughts or suggestions would be appreciated.

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1986 300SDL - 116K
2014 Prius Plug-in (company car)
2014 Q5 TDI (wife's car)

When you changed the engine mounts, did you use high quality ones (Lemforder or Corteco, Not URO)

Also did you change the center mount behind the transmission?

Reason I say is that my center mount is shot and I need to replace it. I have noise on acceleration.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

My mechanic used Lemforder for the engine mounts, and the transmission mount was replaced too. I know before the engine mounts were replaced, I could feel a slight vibration in the steering wheel at idle. Now that is gone.

Using "vibration" to describe the noise I'm referring to may not be an accurate way to describe it. Again, it's nothing that I can really feel. It sounds like it could be a panel or something vibrating in the engine compartment.

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1986 300SDL - 116K
2014 Prius Plug-in (company car)
2014 Q5 TDI (wife's car)

Poke around here to learn about the hydraulic valve lifters. Maybe that is what you are hearing. Mine sound like clicking/tapping which is most noticeable at idle, but you keep hearing it somewhat as the rpm increases.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

Don't overlook the serp belt tensioner arm, shock, and spring. That will make a knocking / rattling sound when it starts to go bad.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I just replaced the shock, spring, tensioner arm, and pulley as well. Big reduction in what seemed to be general engine noise....

Motor was just kinda of sounding "older and louder"...Now quiet like it was many years ago.

I was really suprised. LOL

Also there are two enginge vibration damper shocks we should replace.

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1986 300SDL 440,xxx

Crack in the downpipe, flexjoint, on the exhaust?

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Cheers!
Scott McPhee

1987 300D