Author Topic: Is my oil too thick, resulting in a noisy chain? (Read 3024 times)

cjshelley · « **on:** June 30, 2009, 10:07:32 PM »

I've been reading up on the timing chain issues but don't want to believe that it's time for my timing chain to go. I just bought a '91 318i and I could have sworn the previous owners told me that they recently did a timing chain job. I bought it, everything was awesome, but when I changed the oil I used 20w-50 as per the owners manual recommended. Since then, I've noticed that for a minute or two after starting from rest, I hear noise from my timing chain - it's not too loud, but sounds kind of like a little diesel motor. From my research on these forums, I've seen that that sound means I need to replace the chain/sprocket/the works. However, the noise isn't that loud and it goes away once the oil heats up a bit AND it's really thick oil (I can't really believe it's recommended, but whatever). I didn't notice the noise before I changed out the 5W-30 that was in there, either, so that also makes me think it's just a matter of using oil that's too thick. I was hoping someone might give me some insight before I go buy a bunch of lighter weight oil or buy a valve cover gasket set so I can take it off to check the timing chain sprockets.

DesktopDave · « **Reply #1 on:** July 01, 2009, 08:25:09 AM »

I wouldn't use heavy oil in the summer, regardless of owner's manual. I'm also not sure if it sounds like a diesel that your chain is the culprit...might just be a hydraulic valve adjuster. They'll clatter happily away when they have no oil in their internal valve.

Are you using synthetic or conventional oil?

romeomike · « **Reply #2 on:** July 01, 2009, 11:17:55 AM »

If they changed the timing chain, did they change the timing chain tensioner? Mercifully, the tensioner is much easier and cheaper to replace if they didn't.

Details here

http://www.m42club.com/forums/showthread.php?t=2925

cjshelley · « **Reply #3 on:** July 01, 2009, 04:09:58 PM »

I've been told to check the tensioner, which I just haven't gotten around to yet. I was suspicious of the suggestion for 20-50 (it's conventional oil, by the way). I'll check my tensioner today; I read that if I DON'T hear a bearing rattle then it's shot, is that correct?

cjshelley · « **Reply #4 on:** July 02, 2009, 06:16:21 PM »

I pulled my tensioner out and it seemed okay, but I wasn't sure what to look for. The spring was plenty tight - I actually had to use an open end to create leverage to overcome the spring and thread the cap at the same time. Anyway, I drained the 20W-50 and put in 10W-30 and it seems to have fixed the problem. I called a BMW repair shop to get some advice and was told that 20-50's way too thick and it could be that the oil just isn't going through some of the small passageways until it heats up and thins out.

xwill112x · « **Reply #5 on:** July 02, 2009, 10:26:33 PM »

ive always ran 20-50 with no problems.

sounds like you have a bad tensioner.

JoeDellio · « **Reply #6 on:** July 03, 2009, 02:36:54 AM »

Im running 20W50 right now with 250K miles and no noise, but I have a new tensioner.

I would change the tensioner out regardless, its probably the original one and theyve been updated anyways. Im pretty sure the updated version is a tad bit longer.

cjshelley · « **Reply #7 on:** July 05, 2009, 05:52:51 PM »

I changed the oil out for 10w-30 and the noise is gone - I suppose I'll get a new tensioner, regardless. Thanks all!