Recently on my MY 02 320, I noticed some small tapping sound that I believe comes from the engine compartment. It’s not a metallic sound, rather like some kind of rotary thing hitting a plastic part. It is more pronounced after a cold start, but also detectable with a hot engine. It seems only happening when the truck stops at a light or so. Because it is so subtle, I can’t tell if it happens at freeway speed. What could it be?

The only thing happened prior to this is that I changed oil and put a little bit more(right oil height when cold), so the dash shows Oil High when the engine is hot. I Topsidered some oil out after about 1000 miles and I don’t think it is the cause, is it?

You may want to check the "harmonic balancer" thread in Tech Help...it's the sticky post at the top of the thread list.

If your problem is indeed caused by the offending part, a failure would do some real expensive damage...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car