My R320 was at the dealer today, and among other things, I had them look at a "rattle" that I have sometimes at idle. Sounds like it comes from the rear of the engine. My indie said it is a cracked exhaust flex/accordion part, I'm not real sure what he meant as I don't ever speak to him directly.

The MB tech at first couldn't reproduce the noise(surprise), but as my car was brought around for me I could hear the rattle. Went and grabbed the tech and he heard it, then he grabbed another tech and he said I had a leaking injector. I was advised to have it looked at soon so to avoid "black death". I asked if the injectors could be rebuilt and he said no, that the slide hammer they use to remove them usually destroys the injector.

So, can a leaking injector sound like a rattle at idle? I'm not sure I've ever heard of such a thing.

Good news is the MB dealer has caught things that the indie misses.. I think I need to find another shop.

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08 R320 CDI current

Past
95 E420
87 300D Turbo 5spd
90 300TE
83 300SD
85 300TD
92 400E
85 190D

I don't know about the OM642, but on the OM648 they can be pulled and reused. Having the engine warm helps, and all the "black death" needs to be cleaned out. Of course, i have a 211, where you have plenty of room directly above, so that may be a factor if you dont.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

The exhaust flex is one of the repairs on my om642. It bolts directly to the back of the turbo, connecting the exhaust port of the turbo to the next bits of the exhaust system (a catalyst, I think). On my w211 it was a straightforward DIY repair, but access to that part of the engine bay is wide open. About $200 in parts cost from an Atlanta MB dealer that does some mail order business. The part had to come from Germany, so it took a week.

On my car the symptoms were a dieselly smell in the cabin at idle and some soot on the firewall near the flex. Never noticed any change in the engine sound even though it is an exhaust leak.

The 642 injectors are not servicable, Bosch does not sell parts for them nor will you find a repair shop able to service them. You can remove and test them, it takes patience (which dealers are not known for!) but that is all and a service center with a common rail test bench-they check for flow and leaking. Some have reported that removing and cleaning them on the bench works...but will not solve problems other then carbon build up.

I would not want that repair bill, injectors are expensive ($400+ each) and most likely a complete guess unless you can see with the star diagnostic (idle compensation values by cylinder). I would progress very carefully...there must be some diagnostics that could be run to narrow it down, the 642 is a rather complex engine with lots of stuff that could cause rattles or noises/leaks and other funny stuff...I know!

If you look around sometimes used injectors from Sprinters are out there cheap enough, I haven't checked to see what part numbers cross over as the Sprinter does have lower power output and might have different hardware.