I just finished replacing my delivery valve seals on my '96 and I have the same problem. Now my car sounds like a can of marbles at idle, especially when the engine is cold. I had a similar experience with my ex-'87 300D but that one in addition to knocking more also started smoking and idling rough probably because I didn't tighten the valves down enough. This time though I used a torque wrench and tightened each valve three times to 35 Nm and I did my best to keep the IP internals clean so I don't know what I did wrong. I'm getting the feeling that these OM60x engines are extremely sensitive when it comes to touching the fuel system. After checking the injectors on both cars I also got increased knocking, but on the '96 it went away after some time. I'm hoping the same will happen again this time.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL