I have a E93 335i with about 75,000 miles that I bought from an auction so I have no history on the car. The engine taps and I assumed it was a lifter. I just finished replacing all 24 lifters, the spark plugs and checking/cleaning everything in the head area including making the VANOS gears and solenoids spotless. The engine seems to run OK and has decent power but I have nothing to compare it to. Could a bad timing chain tensioner make a constant loud tap? I am starting to think rod bearing since I am out of ideas. I found a stringy piece of old rubber at the top left side of the timing chain guide. It is likely an old serpentine belt that got sucked in at one time. I reused my belt tensioner when I did the lifters but maybe it is bad and is causing the noise? That seems to good to be true. If it is not that then I can only imagine lower engine like rod bearings? I am at the point where I am not sure if I should try a chain tensioner or just start parting this thing out before I waste more and more money. P.S. My tensioner has a metal gasket so maybe it was replaced already once?
I spent $2,650 on the car, then almost $5,000 more on a water pump, full body kit, M3 fenders, fiberglass hood, xenon headlights, etc. I just found some hidden frame damage in the rear so if the engine needs more work I am probably just parting this car out and losing a few 1,000 when all is said and done.
Sorry for the rant, this money pit has depressed me. If anyone can think of what would be causing a constant tap please let me know. It taps with the RPM's and at idle it is there but when you rev to 1,500 rpm or above it really sounds loud.