E46 M3 Engine Noise - VANOS?
Like some of you guys, I've lived with a certain fear that my engine would give up its ghost because of a faulty condition we just refer to at a bad VANOS. I've had several indy shops and a local dealership check it out over the 2 years I've owned this rig. Also had the valves checked/adjusted because of a strange noise in the front passenger side of the engine. The conclusion is that the engine makes an "excessive and unusual" noise ( NS!) and I need to replace the VANOS unit " as a place to start". Cost - benefit analysis told me to use a different approach, so I reached out to Dr. VANOS for a pair of those cool spline gears they sell. I installed those gears, and the noise is gone. I'm convinced that the bearings in the factory spline gears were the cause of the noise in my engine. I also replaced the VANOS unit with a previously owned unit, and that may have factored into the fix - not sure, but don't think so. If you're going to R&R the VANOS, I recommend taking a look at the roller bearings in the oil pump to see if they're burned or not. If not, I'd consider those spline gear bearings as a possible source of noise / fear of disaster. When you have the VANOS off of the engine, just wiggle the threaded shaft that connects the spline gears to the VANOS and draw your own conclusion.
The car in question is a 2003 M3 with 73XXX miles, SMG convertible.
The usual disclaimers apply here: I'm not a mechanic, don't pretend to be a mechanic, don't have a relationship with Dr. VANOS other than a very well satisfied customer, and could not pick him out of a line-up. Good luck.