Mystery part

[chodedub]

Whats this? It came from that hole in the block. Both the outer sleeve and bolt are stripped, as well this thing has wore a hole in the upper timing case cover and the PO has covered it with JB Weld. What is it and how do I fix it?

[jntar]

#9 and the tensioner rail is what you have there. Replace both, you'll probably have to tap the block to clean the threads out so the new bolt will go in correctly.

http://realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=11_4367&hg=11&fg=25

[chodedub]

#9 is the inner screw what of the rest of the part?

[vpilarrt]

The outer sleeve threads into the head. The threads in the head are probably stripped also. There's no p/n for it on realoem. Don't know if you can get it from a dealer or from someone parting an engine. You may be able helicoil it, don't know.

[bmwman91]

Had this happen to me. Did you replace the driver's side guide rail at some point, where you replaced the old original metal one with the newer black plastic one? The new plastic one uses a 45mm M6 cap screw, and the old one used a 40mm screw. A lot of people forget to use the new longer one and the threads in the head strip. Did you find this because it wore a hole in the timing cover (mine ALMOST did lol), or because it was making awful rattling sounds?

Anyway, you can do the repair without removing/replacing the guide rail, depending on the tools you have available. The threads on that sleeve are M12x0.75 if I recall correctly, and the threading dies for that cost as much as a new guide rail. Mine was all banged up too, but I also have the good fortune of having a lathe which I used to clean up the threads. I basically just chucked it up, ran it at a LOW speed and chased the threads with a small, fine triangle file. If you have a drill press, or a hand-drill and a friend, you can probably get the threads back into working condition the same way. Fixing up the threads in the guide rail isn't as easy, and you'll basically have to (carefully) force the repaired threaded sleeve in.

I did have to install an M6 helicoil into the head. That was relatively easy. I got a shop vac and duct taped some 3/4" vacuum line (or something like that) to the hose and then jammed that down by the hole I was about to drill and tap. I then used a cordless drill on low speed setting and cutting oil to carefully drill out the bad hole, with the shop vac going to suck up the chips. Next I tapped it with the helicoil tap, again with the vac going. Vacuum the crud out and then clean the oil out of the threaded hole (I used a little bit of brake cleaner). Then install the helicoil, and reassemble with the correct bolt.

[chodedub]

I took the timing cover off and it fell out, the PO had the same problem by the look of the jb weld on the spot where it was wearing through again. So just tap and pray basically? Lol

[bmwman91]

Tap and pray...reminds me of my younger years lol. *Ahem*

If you do the helicoil properly, you shouldn't have to pray at all. Just work slowly and methodically and you'll be fine. Or, suck it up and take the lower cover off and replace the guide while repairing the threads. The sleeve thing looks pretty fuxored, so filing the threads back into shape may not work out...the guide could still vibrate a bunch with all the missing metal on the sleeve. And then you'd still need to open it all up again.

Here was my experience. Just for reference and pictures.

http://www.m42club.com/forum/index.php?topic=13720

[chodedub]

I am in the process of tearing down the block the send it in for a refresh at the machine shop, the guides have already been replaced by one of the other PO so they as well as the chains and sprockets are in really good shape. Just this bolt and other thing have been the only problems as of yet, still have the head and oil filter thing to disassemble

[bmwman91]

Maybe see if someone doing a part out will sell you a clean sleeve?