Originally Posted by ngarover

Drove it 300 miles today... ran great, most the trip i was on cruise control doing 70, at some points I hit 90 just to see.... I verified the speedo was correct using my gps.

Before I left I noticed a new A/C belt in the trunk, so I tossed it on, charged the system, swapped the kilma from my 300CD and got cold air. The tach does not work. there are a few times I noticed it try to work when I would really kick it down. The trip including 4 different mountain climbs, some city driving etc... really a taxing trip on the car, but not an issue. So, whatever this knocking is it does not seem to be effecting the car. I did have the car run for a second without the power steering pump hooked up, so I can rule that out. THe A/C compressors tight, since I just did that. When I put my stethoscope right in the alternator, it sounds fine... so I'm ruling that out.

This has stumped multiple mechanics, so I'm not going to feel to bad if I can't figure it out, but It would be a nice feather in the cap...