Author Topic: Wierd idle and running sound from motor (Read 2526 times)

B2thazizza · « **on:** July 15, 2010, 02:28:49 AM »

The motor ran fine until it started making a dieseling sound and very loud clicking that would get louder when i rev the motor and the engine has a big loss in power at any rpm. I pulled the head and inspected it and everything seems fine theres oil in the valleys like its getting there. In the cylinder walls you can clearly see the crosshatching and they look like they where just recently milled thats how clean they are. I havent pulled the oil pan to check the lower pan bolts to see if they are tight or fell out just yet but i suspect that they are blocking oil pickup. What do you guys think i should do?

BlueBMW · « **Reply #1 on:** July 15, 2010, 06:24:23 AM »

The lower oil pan is an easy enough check. Also, when you pulled the head how did your timing components look? Is it possible you jumped time?

DesktopDave · « **Reply #2 on:** July 15, 2010, 07:11:40 AM »

+1 on timing. Check the chain guides and see if the TC tensioner is good. Also check that little gear down near the bottom for a bad bearing.

B2thazizza · « **Reply #3 on:** July 15, 2010, 12:58:39 PM »

The motor has never been taken apart this is the first time, i recently replaced the tensioner to a newer m44 one. I also looked at the chain guides and there is some wear on them but the chain seems fine and is tight with no slack but not so tight that it feels like it could snap. Also what gear are you guys talking about is it the one thats behind the timing case the chain connects to on the bottom?

DesktopDave · « **Reply #4 on:** July 15, 2010, 04:23:34 PM »

Yep, it's an idler gear on the passenger side of the block and has gone bad in a few cases. The m44 edited it out. Your chain does sound like it's in good shape though. The other issue we commonly see are pointy cam gears. They should have a flat top, not a point. You can replace those if the timing is off and save the engine.

Check the timing right away though, that's the crucial thing. You pulled the head, maybe check it for straightness. The valves are all good too, right?

I'm pretty sure that replacing a tired tensioner is a good way to finish off the timing chain guides, but that's just a guess and not really based on solid evidence.