M42 timing chain rattle...revealed!

[billb]

Started having a pretty nasty rattle from 2800-4200 rpm in the 318is. Pretty day today, dove into it. Found a few issues...tensioner rail worn at the top. Bottom guide cracked around one lug. Chain might be a tad stretched. Idler gear looks good, cam gears look good, crank sprocket looks good, long guide looks good, top guide looks good but is $6 to replace. I think I'll replace the chain, update the tensioner to the late M42 version, replace the upper and lower guides and all gaskets, and let her rip. Picture of the cracked lower guide attached.

[Jr ///M5]

But there's no cuts or blood on those fingers...=) Way to go Bill, were you still running on the original tensioner?

I replaced mine when I did the profile gasket 5 years ago. It's been quiet so far, knock on wood, but there has only been about 12k miles since then.

Let us know how it all goes back for you.

Jr

[billb]

But there's no cuts or blood on those fingers...=) Way to go Bill, were you still running on the original tensioner?

I replaced mine when I did the profile gasket 5 years ago. It's been quiet so far, knock on wood, but there has only been about 12k miles since then.

Let us know how it all goes back for you.

Jr

Dad thinks the gear teeth are a little sharp, but I think they're okay. I'll save those for another 50k miles or so. This is to get me through the year in driver's schools...

I'll keep you posted. Thanks for the support!

[winfred]

all of the m42 rails suck and wearout like no other bmw motor i've seen, id do all of the rails and guides and be done with it

[billb]

all of the m42 rails suck and wearout like no other bmw motor i've seen, id do all of the rails and guides and be done with it

But I must admit after looking closely at the cam and crank sprockets, I might want to change them while I'm here. Am I being penny-wise and pound-foolish? The long guide is $41. The tensioner rail is toast, and being replaced, but the other one looks brand new. Trying to get out of this without too much investment.

Here's a shot of the long guide.

[billb]

This one is obviously toast. I'm replacing with the refreshed M44 style, a little different, with a bushing and a bolt instead of the pivot bolt and circlip.

[winfred]

if you plan on keeping it till it drops go for it on the chain/sprockets, i've done several m42/44s and never really found the need to do them, but the rails and guides are crap, i like the early m42 with it's roller at the bottom over the later m44 with it's sliding guide

[Bruno]

Good stuff guys, I have to do a 318i M42 engine with the same rattle this Satruday.
I already ordered all the gaskets and all the chain tensioners.

I wasn't planning on doing the chain. Should I? Do you need special tools for the timing of the cams if you want to do the chain?

How long does it take to do the job? Do you need to pull any pulleys to get at the tensioners? (meaning do I need some tools that I don't have yet.)

[billb]

...and that of Brendan Purcell, a noted 318is enthusiast in Ireland. When I finished it, with all the pictures, it was 72 MB. I'll pull the photos out and send the document to you, and shrink the photos down and email them separately, until I can figure out a way to get this thing to a manageable size. Until then, you may want to visit this link:

timing chain replacement

If I would have had everything I needed, it would've taken about 8 hours, start to finish. I had to wait a few weeks due to travel, parts shipment from BMA, etc.

I have a locking tool that I purchased that locks the cams in parallel relative to each other. It does not have any advance built into it, as some folks like to add some in during their rebuild. I would recommend replacing the chain if you're in there. It only cost $48. I spent about $350, could've spent more if I had replaced the long guide and the idler roller, but they looked okay.

Email me if you are interested in the tool. You can buy a new one for $45 from www.catalystracing.net, but I was going to try to recoup my cost by renting mine out for $15 shipped to the user. Let me know.