I just completed a VacExtractor oil change on my baby and noticed a very distinct rattling sound coming from the engine. I had read about this before but hadn't been experiencing the sound until I changed the oil. Well, I preordered the part and the timing chain tensioner arrived in the mail today so I immediately went out to tackle this very simple task (15-minutes). After replacing the tensioner, I started her up, she rattled loudly for half a sec and then went into super quiet mode. Now I can barely hear the engine running at all because it's soooo smoooth! I HIGHLY recommend this as a preventative measure if for no other reason since avoiding it could potentially cause a plethora of other engine failures due to the plastic guide rails used for the chain...they get chewed up becasue of the loose tensioner, which allows the chain to flop around between the guides, destroying them and depositing all the little bits of plastic inside your engine! Go here to the DIY and do it this weekend to quiet that rattle or avoid potential future failure: http://forums.bimmerforums.com/forum/showthread.php?t=1233696
I believe the original M52TU/M54 tensioner was spring loaded, and the updated design is hydraulic and thus more reliable.
YUP...it was definitely a weakened spring cause the engine is running like new again. I was hoping the sound wasn't the infamous VANOS rattle and it appears to have been the easiest of the repairs. Hydraulic seems to make MUCH more sense since failure of the tensioner can completely ruin your engine from my understanding...
Update on this quick and easy fix. I just completed a run from NorCal to upper state OR and she ran like a dream. Interestingly enough, at one point after taking a break, I'd started the car and before I put it into gear, my wife tells me that I have to start it first! Imagine her surprise when I notified her that the engine was already running... If you have the old spring loaded timing chain tensioner, I HIGHLY recommend doing this as your baby will run like new again.
Engine Rattle I, too, have a chatter coming from the engine but it only occurs when I switch the A/C on and off. Could the increase in engine load be exposing the weakness in my timing chain tensioner? I have a 1998 528i with 106K, BTW. My original suspect was the A/C clutch, which you cannot purchase separately from the compressor.
