Hi, my '98 is giving me fits right now with air in the lines. It causes a lot of "pinging" and knocking problems. I would say try to find the source of the air before moving on.

One other thing I would try is to re-torque the #3 delivery valve holder. Back it off a 1/4 turn and then torque it back down while the engine is hot. I have had good results with this to stop idle knock and shake.

Timing advance mechanism? I'll go out on a limb and say it's virtually impossible for it to fail. When a GP goes bad, these engines sound awful, clacking, shaking and smoking until the cylinder comes up to temp.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250