Author Topic: Help! On road trip and Engine began loud rattle. What is it?/How to Fix? (Read 5684 times)

danegel · « **on:** June 15, 2011, 04:04:27 PM »

On a road trip and two hours from my destination my E36 M42 began emitting a loud rattle. Hard to tell where exactly its coming from but it sounds like its somewhere from the front/beneath the intake manifold. I drove two more hours to my destination and it didn't seem to get louder once it started. Also no noticeable loss in power and I've heard a valve knock before and this doesn't seem to sound like that. So this leaves three questions... 1. What's going on here? 2. How do I fix it? and 3. Is it going to be possible for me to drive this 5 hours back home tomorrow?

This is a video I just posted to youtube that shows the knock/rattle so you can get a better idea of whats going on. Thanks.
http://www.youtube.com/watch?v=Sx2cynn9isE

monty23psk · « **Reply #1 on:** June 15, 2011, 08:49:37 PM »

Sounds like chain tensioner. As you let off throttle, the chain looses tension and rattles. That is my guess. Fix it as then the chain can jump and then its rebuild time. Not sure if there is an easy way to test the tensioner for the e36.

danegel · « **Reply #2 on:** June 15, 2011, 09:42:10 PM »

Thanks for the reply. I've come to suspect the chain tensioner after some researching so I'm definitely gonna replace that when I get back home. I'm still wondering if a 5 hour trip is going to be survivable or if I'm gonna kill my car trying to get home.

VegasKyle · « **Reply #3 on:** June 15, 2011, 10:31:11 PM »

That sounds a lot like when my guide rail broke in half and the chain was slapping around in the case. So I bet it could be a bad tensioner causing the same thing.

monty23psk · « **Reply #4 on:** June 15, 2011, 11:27:55 PM »

just dont rev it really high to cause chain to jump.

bmwman91 · « **Reply #5 on:** June 15, 2011, 11:43:41 PM »

If you are lucky, it is the tensioner. You should pop it out & see if there is anything obviously wrong with it. I had a very similar rattle that developed, and eventually became a cacophony. See here...
http://www.m42club.com/forums/showthread.php?t=13574

Honestly, I would avoid driving the car unless it is absolutely necessary. You are gambling with your motor's life. To be honest, driving 2 hours with it sounding like that basically means that you need to replace the timing chain, and probably a guide or two. Pray that it doesn't jump a tooth if you have to drive it more. Sorry to be the bearer of bad news, I just want to try to save you a ton of grief later by causing some now.

danegel · « **Reply #6 on:** June 16, 2011, 05:54:18 AM »

Thanks for the quick replies...about to hit the road now so at least I know what I'm up against. I'll post pics of the tear down if I make 'er home.

e30boarder · « **Reply #7 on:** June 16, 2011, 07:45:53 AM »

check your oil pan for pieces from the guide rails... just in case

bmwman91 · « **Reply #8 on:** June 16, 2011, 07:25:32 PM »

Yeah, if at all possible, drain the oil (strain it if you plan to re-use it) & pull the lower oil pan to look for debris. I highly recommend investing in a magnetic drain plug...it has saved my ass a couple times now.

Good luck, and I hope your drive home is uneventful!

rojeho · « **Reply #9 on:** June 16, 2011, 10:23:26 PM »

Quote from: e30boarder;104624

check your oil pan for pieces from the guide rails... just in case

Is there a way to do this without removing the oil pan? Would a borescope get a good enough view inside? Really strong magnet on the outside of the pan to lead pieces to the drain plug opening?

VegasKyle · « **Reply #10 on:** June 16, 2011, 11:58:39 PM »

Quote from: rojeho;104640

Is there a way to do this without removing the oil pan? Would a borescope get a good enough view inside? Really strong magnet on the outside of the pan to lead pieces to the drain plug opening?

Most of the pieces will be plastic.

NisseJ�rnet · « **Reply #11 on:** June 17, 2011, 06:25:18 AM »

Quote from: danegel;104622

Thanks for the quick replies...about to hit the road now so at least I know what I'm up against. I'll post pics of the tear down if I make 'er home.

Any updates?

Did you make it home?

e30boarder · « **Reply #12 on:** June 17, 2011, 09:50:12 AM »

yeah your best bet would be to drop the oil pan... you dont want to mess around with random shit floating around in there. itll get real expensive real quick lol

danegel · « **Reply #13 on:** June 17, 2011, 01:34:05 PM »

Thanks again for the help here. 5 hours but I got her home just fine. I found that certain RPM's seemed to resonate just right and the vibration would become hardly noticeable. About 1500 and also 3100 it would quiet out. Very convenient since 3100 in 5th put me at about 68-70 mph so I could keep it on the highway without being the asshole that slows up traffic. I'm ordering my new tensioner and gaskets for timing case and oil pan today and I'll post pics after I get it torn down to see exactly how bad the damage is.

e30boarder · « **Reply #14 on:** June 17, 2011, 02:56:42 PM »

nicely done.. glad you made it home dude