So my OM602 has always made a "ticking" sound. Formerly, it was around 1000 RPM. I had the injectors rebuilt with Monark nozzles - immediately afterward, the sound remained. I posted a video back then, and was told the sound was nailing. As the new nozzles broke in, the sound seemed to go away, and I stopped thinking about it.

More recently, I had the injection pump replaced with a Dieselmeken unit. The motor runs great, makes pretty good power, but the ticking is back in full force. Only now, it is more around 2000 RPM. The new pump was timed differently than stock - it called for 8-10 ATDC rather than the stock (I think?) 14-15 ATDC, so I don't know if that accounts for the change in ticking.

Anyway, you can sort of hear it in the video below. Unfortunately, it's difficult to fully capture the sound while sitting in park - but if cruising around 2000 RPM, the sound is more or less constant.

Any ideas what it might be? Lifters, maybe? Or is it really nailing, even though I'm running a basically new injection pump, fuel lines, and injector nozzles?

https://youtu.be/c6fyNRm1hLg

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That's fuel knock. I'd say it's because the injectors aren't balanced and pressures adjusted to handle the increase in fuel and different injecting timing other than the stock setup.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Egads tho...

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Yeah, but I had the sound before the new pump and injectors as well, just lower in the power band. Injectors were rebuilt and balanced by greazzer, so I know it was done right.

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I think it would be maybe a bit easier to get a better listen to the sound if you did it hood up in the engine bay style. It could be a mechanical sound not related to the pump or the injectors.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
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1978 300CD "El Toro"

Have you checked the belt tensioner damper? The end bushings can wear faster than the damper body so it works but sounds like the engine’s coming apart. Use a dowel or long screwdriver to put pressure on the ends to see if the sounds goes away or changes.

Sixto
98 E320s sedan and wagon

Yeah, I know the video is poor quality. I'll try to get a better one with the hood up, just need to get a helper. Honestly, it most noticeable and easiest to replicate with a little bit of load on the engine (i.e., driving), but I don't think that would make for a very good video, either.



Belt, tensioner, and pulleys have all been recently replaced.

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Certainly not lifters.

It could easily be timing. I would get the chain stretch checked, verify cam timing and get the IP set to factory.

Why was it set where it is?

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Timing chain was replaced about 18 months ago. I assume cam timing would have been done at the same time? IP timing was at the recommendation of the pump builder (Dieselmeken), although I never got a solid answer on why his pump calls for different specs.


But again, the noise existed before the stock pump and injectors were replaced, except that it happened around 1100 RPM.

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be sure and check crank bolts on pulley,and flex thing on flywheel.

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