2011 Z4 35i sdrive

[bpayne]

Mechanic blew up old engine. Replaced with lower mileage z4 35i engine. After having significant turbo problems (rebuilt both), now have valve train clatter issue. Whenever accelerating or decelerating, the transition from load to no load and reverse induces valve train clatter anywhere from 1800 to 3500 rpms. Important to note: going from full load (uphill, 5% grade or more) to a "hold" rpm induces horrible valve train clatter. Same for reverse: Going from no load downhill to moderate rpm "hold" as you approach a curve for acceleration through it, induces horrible valve train clatter.

The BMW tech said change viscosity in the oil. It helped, marginally. To me, either one of two things: IF it is oil related, there must be a "starvation zone" that to me indicates a blockage of some sort. It has a new elec oil pump, so my guess would be in the lines. Important to know, the asst mechanic crushed the oil filter which makes me believe he put the wrong one on, and is why the oil viscosity change wasn't the real help, the correct oil filter was.

Second issue - to me is related to variable valve timing. if the intake and exhaust valve sensors were bad, that could be "the thing." But, not likely both are bad at same time. Worth replacing (mechanic's dime). BUT, I am leaning toward crankshaft position sensor. BTW - did a test for worn belt and/or pulley tensioner issue. Negative on both.

HELP. My wife loves this little rocket ship. Mechanic IS BMW certified - doesn't mean he's good. But he has been very responsible - hasn't charge me a dime. But he's had it 4 months (after 1st replacement engine wasn't as advertised) and he's close, but nobody is striking a match for that cigar.