Originally Posted by Diseasel300

Unless you have serious chain stretch from extreme lack of maintenance, IP timing and base engine timing are the least likely to be your issue here. 60x engines just don't eat chains like the 61x engines do and there's no offset keys to adjust cam timing either. I've serviced 603's with 300-400K on them and the original chain with 1-2˚ of stretch and left them well enough alone.

I would have hoped that my previous reply about the delivery valve leaking would have been heeded, but nobody ever listens to someone with experience, so why am I not surprised? There's a reason I rarely contribute to this forum anymore. The injector isn't the issue, it's delayed or improper combustion. I've dealt with many 60x engines with this noise and DV's generally improve or eliminate the issue. Newly rebuilt injectors shimmed to the correct pop pressure always seem to exacerbate a leaking DV compared to an older worn/weak injector. The older engines with the "vertical" injection prechambers are far noisier and always have a certain degree of a metallic "cackle" at idle. Some degree of knock is to be expected and has to be tolerated.

In this case, you have a combustion problem, likely a leaky DV or worn DV seat. Air in the return lines is normal. You don't normally see it with the black/grey rubber ones and it takes a LONG time for it to work its way out. The leakage through the return/leak ports in a well-lapped injector is very small, so the flow through those lines is minuscule.

Originally Posted by Diseasel300

Unless you have serious chain stretch from extreme lack of maintenance, IP timing and base engine timing are the least likely to be your issue here. 60x engines just don't eat chains like the 61x engines do and there's no offset keys to adjust cam timing either. I've serviced 603's with 300-400K on them and the original chain with 1-2˚ of stretch and left them well enough alone.

I would have hoped that my previous reply about the delivery valve leaking would have been heeded, but nobody ever listens to someone with experience, so why am I not surprised? There's a reason I rarely contribute to this forum anymore. The injector isn't the issue, it's delayed or improper combustion. I've dealt with many 60x engines with this noise and DV's generally improve or eliminate the issue. Newly rebuilt injectors shimmed to the correct pop pressure always seem to exacerbate a leaking DV compared to an older worn/weak injector. The older engines with the "vertical" injection prechambers are far noisier and always have a certain degree of a metallic "cackle" at idle. Some degree of knock is to be expected and has to be tolerated.

In this case, you have a combustion problem, likely a leaky DV or worn DV seat. Air in the return lines is normal. You don't normally see it with the black/grey rubber ones and it takes a LONG time for it to work its way out. The leakage through the return/leak ports in a well-lapped injector is very small, so the flow through those lines is minuscule.

Originally Posted by JHZR2

I still get a rhythmic metallic tapping at a slower frequency. Maybe that’s the lift pump or something? I notice it’s most pronounced at hot idle and when driving in high gear at low rpm, 1100-1250 call it, where I hear it most pronounced.

Originally Posted by gmog220d

Vacuum pump?

Originally Posted by JHZR2

Replying again to let you know that I have taken your advice and did the DVs today.

Removing the intake is the biggest hassle. Not hard, just a hassle. DVs were easy. A mess, but easy. I used compressed air and cleaned as best as I could.



O-rings were hard as would expect.



And the old crush washers had a slight wear ring








Torqued them as per the instructions.






It took some cranking to get the air out, but it worked out ok and fired up. It still has a knocking sound, and what I’m seeing is a lot of more frothy bubbles in the first cylinder return hoses. I think I do need to go back to the regular rubber ones to seal a bit better.

Anyway, was going to take it out until I saw that my turbo brace/stay was cracked and fell off. So now how to repair that…

Originally Posted by ah-kay

I think you need to sit down and have a cup of coffee. You are confusing about your OM602 ( turbo bracket broken ) and OM603 ( DV replacement ).

Originally Posted by JHZR2

Huh? No.

I have a lot of diesels as you can see from my signature. The knock that pushed me to work on lifters, injectors, and then DVs is for the 602 in my 91 300D 2.5.

I did have an issue of misfire/broken cam due to bad work from an MB shop, on one of my 1991 350SD cars. But that’s entirely separate.

Injector knock is only associated with my 1991 300D - the only cross between them is that the 603.97 and the 602.96 both use the same model injector in the angled design.

Edit - I see you edited (I had quoted your original which has changed). Perceived? It’s definitely noticable in terms of the difference between this 602, and my 601/603 engines. Let alone my 616/617.

Originally Posted by ah-kay

Good luck with the fixed. If I were you, I would push them off the cliff. Out of sight, out of mind.

Originally Posted by jdulle

Mine does something like this, it seems to make the most noise at 1,200rpm, and sounds fine over 1,800. Mine also vibrates a lot at idle, which my mechanic assured me was just the engine mounts. If you figure it out great, but I don't think it's going to stop the car from going thousands or hundreds of thousands of more miles. Are you getting good power and economy?