Hole in upper timing case...

[beemer]

I've been trying to locate a recent heavy oil leak. Then I found a hole in the upper timing case :eeek: After removing the valve cover and upper timing cover I discovered that the drivers side timing chain guide bolt had snapped and the spacer had backed out. Both the broken bolt and spacer were resting on the case and eventually made a hole. The threads on both the M6X1.0X45mm guide bolt and the M12x0.75 guide spacer have been flattened and unusable. So far I had found a similar grade 8 M6 bolt from home depot that needed to be cut to correct length and rethreaded. But my problem is finding a tap and die locally for a M12x0.75 is nowhere to be found.

Can I rethread a M12x 0.75 to a M12x 1.50?

[bmwman91]

Wow, it actually happened.....

I don't think that the sleeve is available for purchase on its own. You can probably find someone in the for-sale section parting out an M42 and that would get you the spacer and upper cover pretty cheap. Maybe the 45mm M6 bolt too (or you can go on McMaster). You are obviously going to need to helicoil the head too. You can do it without disassembling things too much if you tape a piece of rubber hose to a shop vac hose and stick it in there while you are drilling to catch all of the metal chips. Thankfully, the hole that the spacer goes into is plenty large enough to allow through the drill bit you need for an M6 helicoil.

And no, you should not fudge a solution here and re-thread it to something else. That sleeve sees some fairly hefty forces from the chain and weakened threads will just strip, or allow too much movement of the guide and it will crack.


Random backstory:
A few years back I had almost the same thing occur on my car. Thankfully I found it before it wore through the cover, but it definitely got about 1mm into the metal lol. Prior to that I was having a weird metallic buzz/rattle at ~3000RPM and I just couldn't figure out what it was. After finally sucking it up and popping the upper cover off I discovered the cause! Anyway, that did leave me wondering if it would ever wear completely through the cover, and now I know!

As for the M12x0.75 thread, I looked around for a couple of hours and did manage to find a Metric hardware specialist somewhere in the midwest that listed one online. It was something like $100. Since I did not have the time for that, and I could buy a replacement guide with a new spacer for less money, I did not buy it. Instead I chucked up the damaged spacer in my lathe and used a small triangular file to clean up the threads. It wasn't perfect, but it was enough to get it to all go back together since I really did not want to have to pull the crank damper bolt off (I had just rebuilt the timing case 11 months before this).

[beemer]

Yeah I think I read your post on m42 club lol! FML I did a rebuild about 7 years ago and its been oil leak free. Ill post pics either tom or sat of the hole in the cover. I cant find the sleeve for sale anywhere and noticed it comes with a new chain guide. More money down the drain! I'll have to track down a m6x45mm, I believe I saw a pack of 10 on ebay. I also saw on ebay someone selling a m12x 0.75 tap for the guide threads. Is it an option to retap the guide and pray that I could track down a sleeve instead of buying a new guide altogether?

"M42....The gift that keeps on giving"

[bmwman91]

"M42....The gift that keeps on giving"
Yeah seriously. I have had too many "fuck this engine" moments to count. But, I just can't bring myself to get rid of it lol.

The threads in the rail should largely be fine. Maybe the front most one is a little messed up, but I bet that the rest of them are fine. You can probably force a new sleeve through from the rear to clean up the banged up thread on the front. So, just get a hold of a replacement sleeve (someone here has to be parting out an M42). Or buy a new guide rail just for the sleeve...it is probably cheaper than the required die, and re-threading the mangled sleeve will just weaken it.

As for the high strength M6x45 bolt, get on Mcmaster.com and get one. You don't want to take chances with eBay mystery bolts. Mcmaster sells legit, industry standard-conforming stuff. Mcmaster is the shit.
Boom: http://www.mcmaster.com/#91290a204/=whilgp
$5.50 for 10. Grade 12.9. No nonsense.

[bmwman91]

Also, just as a general guideline, NEVER use Home Depot, Lowes, OSH, or other big-box store fasteners on your car. They are all imported garbage that you can NOT expect to meet the strength grade that they claim to have. Fastenal is the only retail chain that I can think of that sells fasteners that meet stated specifications. Obviously Mcmaster does too, but they don't have nation-wide retail stores.

[beemer]

Yeah I might "fuck this engine" tonight with a sledge hammer after trying to remove the mechanical fan. And I will for sure buy a true m6 bolt from McMaster or the likes. This car has been my DD since 1997...a lot of years and miles behind the wheel. Just when you thought you've seen everything and then there is a hole in the timing case....FML

BTW if Im going the distance in removing the lower timing case I may as well change out the guide as well...now that I think about it I may tear it down and do a head gasket job. Can I remove the head without removing the cams?

[bmwman91]

Yeah you can pull the head without removing the cams. Don't forget to clean all of the oil/coolant out of the bolt holes in the block before installing new head bolts.

[beemer]

I had to put the timing case and valve cover back on and roll it out of my garage to make way for my Benz. Today I'm giving it new pads and rotors, brake fluid flush, trans flush, transfer case and both diffs flushed. Once I finish, the e30 will get some pampering, but I will try to back in the spacer once I have the guide removed. Thanks a lot man, I will for sure be back to ask more questions as I never removed a head before.

I was in a rush to put the timing cover back on last night that I forgot to snap a pic of it. There will be more to come.

[bmwman91]

So, almost unbelievably, there is an M12x0.75 tap on Amazon for less than $20.

http://www.amazon.com/12mm-0-75-Metric-Right-Pitch/dp/B00JQ21KMK

If you are planning to re-use the guide, you may as well get the tap and clean the threads up with that instead of jamming the spacer sleeve through it. Honestly, if you are going to be yanking the head and whatnot, I'd say you should just replace the guide while you are at it. Hell, maybe think about swapping in a late model M42 timing case (it uses a plastic guide instead of that awful deflector sprocket). Maybe see what all is worn and do a rebuild (or partial) on the timing bits. That idler sprocket is another notorious failure point on the E30 M42. It killed my engine about a year after I fixed the issue that you started this thread about. If the bearings don't blow out, it will just eventually snap off of the timing case entirely! The later model M42 timing case takes care of that. With the head off, a timing case swap is absolutely trivial.

[///M42 sport]

You need a upper timing cover? What else do you need? I have two m42 engines just sitting in garage that I can part out.

[jrobie79]

I have one sitting in my backyard as well....once the snow melts I'll be able to get to it

[alco]

Can you post pictures of the damage? I have some M42s that I was hoping to use in a couple of projects and this has me concerned. What's preventative measures can one take?

[beemer]

Sorry guys that it took me awhile to respond to this thread. I purchased both the tap and die. Got started on it today and so far so good the guide is savable. I'm just waiting for the fed ex guy to show up with the helicoil kit and I should be good to go! I took pics as I disassembled the timing case, I post them later tonight. Crazy to see a hole in the timing case lol

[beemer]

Lets see if you can spot the hole, kinda like spotting waldo
[IMG]image by smchiro410, on Flickr[/IMG]

There it is! It was a little difficult to find because the metal tab from the cps wire was covering most of it.
[IMG]image by smchiro410, on Flickr[/IMG]

Another angle...
[IMG]image by smchiro410, on Flickr[/IMG]

The culprit..The spacer guide in this pic shows the first 1/3 of it is rethreaded. In the middle you can see it is really shiny and the threads are flattened out. I began to rethread it before snapping a pic.
[IMG]image by smchiro410, on Flickr[/IMG]

Here is a close up of the m42 timing chain guide spacer with the first 1/3 rethreaded
[IMG]image by smchiro410, on Flickr[/IMG]

That guide spacer did a good polishing job the inside of this upper timing case lol!
[IMG]image by smchiro410, on Flickr[/IMG]

This is how the hole materialized.
[IMG]image by smchiro410, on Flickr[/IMG]

This is a pic of the new cover (on the left) and my old upper timing cover (on the right). Look how much cleaner my old cover looks compared to the used one I bought. I've used nothing but Mobil 1 over the course of the last 18 years and it shows!
[IMG]image by smchiro410, on Flickr[/IMG]

[beemer]

I want to thank you guys for your hospitality. I bought a new cover several days before I began this thread and then decided to use a tap and die. It worked and I should be on the road tonight, thanks again