head bolt is pulling out - how to fix?

[rob650]

Howdy,

Tonight, I pulled off the valve cover to start doing a valve adjustment on the right side of my '82.  I found one of the four nuts that holds the rocker assemblies loose.  I went to tighten it with a torque wrench, but it wont tighten down beyond about 15 ftlbs.  Taking a step back, I can see this particular bolt sticks out above the assemblies about 1/2 inch more that the other three.

How does something like this get repaired?  Thanks for any advice.

I just replaced the valve tube seals a couple of months ago - kicking myself for not noticing this last time I had everything apart.

[Justin B.]

The hole has to "carefully" have a threaded insert or Heli-Coil installed.  I never torque mine past 20 lb/ft as the upper rear stud (maybe both upper, I can't remember...) has this weakness on ALL Airheads.

[rob650]

does this take some skill worth paying another guy to do it?  I've Never worked with heli-coils before.

[MrRiden]

Justin,
Good info! I've not been aware of this before! to bad we don't have a separate tech file.
rich
off to Florence, AZ in the am

[Justin B.]

Rich, we do, it's called BMW Technical Q&A!  I think the stud is prone to pulling out because the oil supply hole goes through the threads on this hole which logic dictates to me weakens it.  You can clearly see the oil supply hole in this pic of my '81 R100 when I did a top-end overhaul a couple of winters ago:

[Justin B.]

Rob, this operation requires that the stud be removed (easy), the existing hole drilled absolutely straight and true (not so easy) to the proper size, this oversized hole is then tapped (fairly easy), and finally a thread insert or other thread repair product screwed in (snooze-easy).  A Heli-Coil kit will come with the proper tap and installation tool and will advise what size drill to use.  Heli-Coil is a brand name product that is a little stainless steel coil that puts "new" threads back into a stripped (but properly drilled/tapped/prepared) hole.

I seem to remember having read somewhare that there is a product specifically to repair Volkswagen stud holes that also works great (better) for this as well.  Hopefully somebody will chime in...

[rob650]

Thanks Justin.  I've been doing some reading on HeliCoils tonight, figuring out if its something I can tackle.

[MrRiden]

Rob,
These might be worth a look as well as the Helicoil
http://www.timesert.com/index.html
rich

[nothing]

Rob,
These might be worth a look as well as the Helicoil
http://www.timesert.com/index.html
rich

BMW specifically recommends against using a Timesert in this application - they can block the previously mentioned oil supply whereas a Helicoil will not. There is a service bulletin about this, and Snowbum talks about it on his page about engine internals.

[MrRiden]

Well, yes I see now. Not only are the Timeserts considered a bodge  even if you cobble it together with a Helicoil you may be in error. Seems there is a special Helicoil [1111338630] for the job that has 3 more turns than the commercially available one. Even a repair kit [88886112730] from BMW. The learning curve continues.
rich

[rob650]

Thanks everyone for the advice - I'm convinced Ill need to take it to someone to get this done right.

Any local (SF Peninsula) Heli-coil experts in the area?

[nothing]

Well, yes I see now. Not only are the Timeserts considered a bodge  even if you cobble it together with a Helicoil you may be in error. Seems there is a special Helicoil [1111338630] for the job that has 3 more turns than the commercially available one. Even a repair kit [88886112730] from BMW. The learning curve continues.
rich

The special BMW helicoil is not longer actually. I had read that and ordered a couple. When they came in it turned out they were just standard length. I ended up using a double length helicoil that I had gotten in a old kit marketed for aircooled VW crankcase stud thread repairs.

The part number for the special BMW helicoil is actually 11-11-1-338-630, not 11-11-338-630. Snowbum missed a 1 in his article.

[MrRiden]

The part number for the special BMW helicoil is actually 11-11-1-338-630, not 11-11-338-630. Snowbum missed a 1 in his article.

I went by the A & S parts listing and found both #'s seem to generate a hit for a $3 part.  [smiley=3stooges.gif] Wonder what VW gets?
 As far as someone in Robs area to do the werk, Isn't Tom Cutters shop nearby?
rich

[Justin B.]

Actually, he's out east:

http://www.rubberchickenracinggarage.com

[MrRiden]

Duh-Oh! I meant Ted Porter
http://www.beemershop.com/
I'm not doin' to good here, think I'll just lurk-a-while
rich