My 04 X5 4.4i has been rattling like a diesel from startup... sometimes it gets somewhat quiet after holding RPM's high but goes back to a normal state of clackety clack like a bad cylinder wall.

It runs great, has power, and idle is much better. Torqued the NGK's to 20 lbs for all 8 so it isn't the "tightened spark plug" fix I hoped for.

I did notice that the sound ceases when you let go of the throttle (very briefly) but once the needle goes back down, the engine recommences clacking.

You can feel the vibration from the cabin. I just received my diagnostic cable so I'll be updating this thread with the error codes.

From research I've found several horrible (and some not so much) possibilities here:

alternator bearing
intermediate levers
cylinder wall scoring
valve noise


Would love to get your input on this, I just went through the arduous tasks involved in replacing the valve cover gasket on the left side and hoping that the nightmare ends soon. Thanks!

Update:

Went for a drive again, I'm getting several sounds on top of each other:

1. clickety clack that is throttle dependent (noise accelerates with throttle, then slows down again with rpm's)
2. an almost electric pinging noise that is intermittent, like the ambient noise made when someone turns on a CRT monitor or tube tv behind you
3. this is the scariest part: i get a "crunching noise" randomly that sounds like the engine is chewing on bolts, or can be loosely described as a dull grinding noise.

the car accelerates very quickly. the idle seems much more solid after i put in NGK 3199's (laser platinum), but that's about the only positive outcome. will update with the diagnostic results from the cable.

having a lot of trouble sourcing the software for the inpa cable. not sure i'll be able to have it ready in time to check tonight... please let me know what you think regardless