My 92 300e (2.6) is also experiencing this *exact* issue. It seems to exist reguardless of what oil brand/viscosity I use in the car. I Just changed the oil a few days ago, and did notice a small connector/sensor piece that appears to be directly behind the oil filter housing (it appears to be attached to the housing itself). Could this be this mystery part? Would this be the "valve" or the "sensor" (is there a difference?)? My "tapping" lasts for approx 1-2 seconds, primarily when the engine is cold and is turned on. My feeling is that oil is somehow being "starved" from the top-end initially during those first few seconds, hence the noise. Is this "Check valve" that has been mentioned - is it designed to hold the oil (ie. make a supply of oil available for the top-end, after shut-down)? If so, i am guessing this is failing on my car .. any suggestions? is this a costly repair? (*crosses fingers*)
Thanks all.. input is welcome on this!
92 300e 2.6, 126k