I have a noise in the front of my 1998 E7, sounds like gear on gear chatter, only happens when the engine is warm. Originally I thought it was the water pump since the seal was weaping, so I replaced that and the fan clutch, next the alternator, then the harmonic balancer. Now I have the pan off, the cam bearings look good, cam lobes look good (not roller lifters), crankshaft end play seems fine, timing gears are tight and not worn or pitted, push rods are straight, cylinders are not scored, and last the aux shaft from the timing cover to the air compressor appears to have tight bearings. I'm down to the air compressor which is a bendix replaced about 100,000 miles ago, could that be resonating back to the front of the engine causing the noise? The power steering pump has some play in it but I don't think that is the problem. Last thing I found that I don't know anything about is the econovance solenoid has a big crack in the coil, could that be causing the engine to be too far advanced and creating a pinging sound? The sound goes away for the most part when you rev the engine past idle, and there is no excessive smoke, any experience or advice on the solenoid and its function would be appreciated.
