R90/6 Cylinder Head Cover Bolt Stripped

[zenduddhist]

I purchased a 1975 R90/6 and was checking the valves. After removing the cap nut on the cylinder head cover, it appears the cylinder head is stripped out where the stud bolt attaches. Looks like the previous owner put in some "filler" material and then put the stud back in and reattached the cylinder head cover. I may not be using the correct terms, but it is the stud bolt that is directly in the center of the cylinder head cover or valve cover...

Can anyone give me options for a fix? I know I can buy a new or used cylinder head, but besides that, any ideas? Is there an acceptable filler material that will allow me to rethread the stud bolt into and be strong? JB Weld, maybe?

Thanks,

Chris

[20774]

Somewhat common...been discussed before...here's a thread:

http://www.bmwmoa.org/forum/showthread.php?t=59946&

The center nut shouldn't be tightened all that much...in fact, it might not be needed all that much. If it doesn't leak, then press on. Otherwise, read some of the options to fix. Consider an easy fix first, then maybe when/if the head comes off consider a more permanent repair.

Good luck...

[Stan_R80/7]

That happened to mine circa 1990. I put M8x1.25 recoil screw thread inserts (i.e. helicoils) in both cylinder heads for the valve covers. The stripped thread hole makes it difficult (although, not impossible) to cut the new threads incorrectly with a tap. Keep the tap straight, use WD40 on the tap as lubricant, and cut no more than one revolution before removing the tap to clean off the cuttings. Anyone with reasonable mechanical aptitude and attention to detail can successfully install a thread insert.

[roncooper]

That happened on my 75 60/6. I used JB Weld to fasten the stud in the head. Lasted for years.

[zenduddhist]

Thanks for everyone's input. I fixed it with a Helicoil insert. Works great...