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Valve Cover Bolt: stripped threads

17K views 18 replies 11 participants last post by  fradsham 
#1 · (Edited)
I've read a few posts here that caution against torquing the valve cover bolts to the 69 in-lb factory spec. Sadly, I didn't find this until after I stripped the threads in the head, in one location. See attached photo.

So, my question is, does anyone here have some experience with fixing this problem? So far, I've thought about (1) drilling & tapping some new threads, (2) installing a helicoil, or (3) epoxying a stud in the hole, and using a nut instead of a bolt to hold down the valve cover.

Any advice y'all can provide would be greatly appreciated.
 
#3 ·
I think a helicoil would be your best bet. In my job I have dealt with broken and or stripped bolts countless times. Most likey there would not be enough good material to retap any good threads. The epoxy set up may not hold depending on the amount of torque. Using a stud may interfer with getting the valve cover off & on. Let us know how it turns out.
 
#5 ·
i don't recommend drilling and tapping, nor helicoils if you can avoid it. beleive it or not, what works the best i have used it the Grab-it (as seen on tv) you laugh but i have used one (the same one) to extract over 30 fasteners on one helicopter (Corroded floor screws) you tube it... if you havent seen them, sears has the, you just need a reversable cordless drill (preferably with speed control and a high torque low speed setting) i.e. de-walt 18 volt cordless.
 
#7 ·
I second the Grabit. They do work.

As I read the OP, it's not removing the bolt thats the issue- sounds as if it's already stripped the female threads and that's what needs the helicoil. I've not checked out the head/vc assembly, but I would lean toward running a samesize tap into the stripped hole and inserting a stud with JBWeld. Nothing lost if that dosen't work. You can drill for the helicoil just as easy if the stud doesn't hold.
 
#8 ·
Thanks for all the advice thus far. Just to clarify, I don't have a stuck fastener, instead I stripped the female threads that one of the valve cover bolts threads into. I tried to attach a photo, but it didn't seem to work correctly.

Anyway, I'm leaning toward a heli-coil repair at this point. Won't be able to get it done until Friday (my next day off). I'll follow up when I get it fixed.

Sounds like that grab-it tool would be a good investment for the toolbox.
 
#10 ·
What size helicoil are you using? Yep I have a stripped bolt hole threads in the head. While looking down on the engine - the North East bolt hole.

What size helicoil?
What size drill bit?
 
#12 ·
I just got the head back from the machine shop; haven't finished putting the bike back together, so I don't know yet how its going to work.

I don't know what size helicoil is needed, but the valve cover bolt is an M6. The reason I don't know is I took the head to a machine shop to get the helicoil installed. I don't have the tools (or nerve) to drill out those threads.

If you want to learn more about helicoils, check out www.emhart.com.
 
#14 · (Edited)
Dang, how was this hoary old thread resurrected? More-or-less 3-1/2 years old, looks like to me.

Regardless, the fact of revitalization indicates the lasting value of the information.

A parts fiche will identify the bore and pitch of the hole; I'd imagine a corresponding Heli-coil would do the job.

Fiche and associated parts list no help? A decent hardware store has a "Find-A-Thread" exhibit, with studs and nuts of different sizes and pitches for your examination; take a bolt in and ID what you need.
 
#17 ·
Been there done that! :mad0235:
I stripped the front right cover bolt hole on my KLR when I was done with a valve adjustment, everything went great until that point.
I used a standard 6mx1 helicoil, worked perfect. I bought a "Coil-sert" kit that came with everything you will need, drill bit (1/4"), tap, coil insert tool and helicoils, it was right around $50 at my local fastener shop.
The hardest part is making sure that you drill the hole completly straight. I was going to make some kind of a guide but when I put my cordless drill upto the bike in a test I realized I didn't need one. With the drill I was using I was able to just rest the body of the drill against the frame and it was straight and for the other direction I made a mark on the frame and used that as a reference point and kept my...thumb I believe on that mark.
Before you drill, stuff a bunch of rags into the head to keep all shavings out of the engine. Drill slow, the head is pretty soft aluminum (as you already know), you will go through it fast.
Again when you are tapping the new threads for the coil go slow and make sure you are straight, and then insert coil and your done!
Its actually pretty easy, the key as you might have figured out is SLOW and STEADY. I have been running with my helicoil for over 10k miles and I have pulled the cover off many times and its like it was never damaged in the first place.
Hope this helps.
 
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