Broken head thread that attaches the valve cover (FIXED!)

Edit: Rick's method of the JB Weld worked really well, if you experience this issue just follow his steps later in this thread.

Well I was on a roll last night. Successfully fit the helicoil insert into the sparkplug hole, was pretty pumped and decided to fix the leaking valve cover gasket. I switched it out with one from my parts bike and on the 4th bolt the valve cover cracked, bad, about 4 inches. This was my fault I couldn't fully remove the old gasket that was attached to the head and I scraped as much as I could and tried to apply the valve cover. After this I switch back to the leaky one to get me to work today and as I'm fitting the last bolt, I feel the bolt give up and to my dismay, the threads have come away from it.

Now I have to pull the head from my other bike and attach it to this one. This is what I tried to avoid with the sparkplug insert.

Can it be done without the following:

Pulling the whole engine
Draining the oil


Will I be in for a terrible time with this?

Will my valve clearances now change or do the valves not come out with the head? My clearances are way out of spec for the replacement head.

Can someone please direct me somewhere I can find details of this process?


Thanks, any input and suggestions will be greatly appreciated.




Edit: Rick's method of the JB Weld worked really well, if you experience this issue just follow his steps later in this thread.

 

Re: Broken exterior head thread that attaches the valve cove

Online Repair Manual.

Can you extract it with extrator bit?

You can do the head with the motor in the bike. You'll make the same mess with oil and I dont believe you'll have a problem contaminating the oil in the bike aslong as your parts are good and clean. If the valves and cam your using now are good, it should be pretty close. You will have to lap the valves into the new head, inspect the journals of the new head, and recheck all valves after its back together. Dont forget fresh gaskets and new head bolts for this job. XJGurus will chime in soon im sure.

 

Re: Broken exterior head thread that attaches the valve cover

Clean the Hole with Carb Cleaner.
Clean the Hole with Alcohol.

Mask the Hole.
2 Layers of tape.
Peen the Tale to Open the Hole.
GREASE the Tape surface,
Smear. Not heavy.

Buy a Brand New Metric Bolt of the same thread pitch as the stripped hole.
Oil the Bolt.
Shake-off the excess Oil.
Apply (2) Two Layers of Teflon Tape over the Threads of the New Bolt with the Oil Sheen.

The Bolt is Taped.
The Hole is Masked.

Mix some J-B Weld.
Drip some right into the Stripped Hole.
Coat the Teflon Tape.

Insert the Bolt into the Hole.
Screw it in like if fits.

Before the Mix sets ...
Remove as much of the excess as possible.
:: The more you get now, ... the less you have to deal with after it hardens.
Make sure the Bolt gets positioned properly.

Let the Mixture CURE.
===> Several Hours Later ...

Remove Bolt, Masking Tape and dress and clean the area.

Repair is good for 7.75 FtLbs.

 

Re: Broken exterior head thread that attaches the valve cover

@Squidjob. Read through the sticky for the carb drain screw removal, there the guys deal with and talk about different extraction bits they've had experiences with. If the bolt is located on the outter edges of the cover, then you might wanna look into that option first.

 

Re: Broken exterior head thread that attaches the valve cover

Rick you are the man. I was really hoping to get a response from you and you've gone far and beyond with some great advice. I reread my post and realized my wording could have been better. I do mean that the threaded hole, that secures the valve cover, threads broke away on the side away from the engine. My hole now is a 'C' shape. The entire thread wall came off so that I can see into the threads from the side. It is the furthest left and front bolt hole. Reading your description of the process I believe it will work for my situation. I already picked up some JB Weld and was going to attempt some sort of reattaching of the thread piece but this is much much better. I am a bit unfamiliar with a few of your terms however, could you clarify:

"mask the hole" - I assume you mean make a sort of pouch/pocket with masking tape to keep the JB Weld in place to shape the structure.

"peen the tale" - I've never heard this expression



Do you think its better to get a bolt about a 1/4" longer than the current one to ensure it wont bottom out when i reinstall?

Thanks again Rick, you've helped me keep my sanity for another day.

 

Re: Broken exterior head thread that attaches the valve cover

That's peen the tape...

 

Re: Broken exterior head thread that attaches the valve cover

No. Just thread one in further than it will be with the valve cover and gasket in place.

This is a good example of what JB Weld is good for. Done carefully, you can build up a new "corner" on the broken spot; then grind/sand it smooth, and very carefully file the top flat to match the gasket surface on the head. You can also carefully "chase" the threads with the correct size tap if need be.

Build the JB Weld up in layers if necessary.

 

Re: Broken exterior head thread that attaches the valve cover

Mask:

Place Masking Tape on surfaces where you do not want the J-B Weld to stick too.
Protect.

"Peen the Hole"

With the Ball-end of the Hammer, ... Tap the Tape above the Hole. The Tape will give and a hole will be made through the tape. Remove the little disc that gets cut.

Mask vs. Dam:

Mask protect surrounding areas from the JB attaching to the non-masked surfaces.

Dam: Make a little containment area to allow the JB to collect.

Effective in replacing a section of a broken-off case.
Like the Dry area of a Crank Cover.

You tape-on aluminum screen to bridge the gap.
Smear JB Weld into the Screen.
Remove Tape.
Build-up JB Weld over that held in screen.
Grind and sand

 

Re: Broken exterior head thread that attaches the valve cove

Well, thanks guys. That JB weld really did the job. The only deviation was a brass colored screen from ACE. It was the only one they carried and was from a faucet screen pack. I was able to nearly exactly shape that same round thread space and reinforce with the screen. Worked wonders and with the new ATV black I put on, there is nigh a leak from the valve cover a week later. You guys are awesome and have some great quick fixes for the bozos who find themselves a bit screwed. Thanks again! Now onto the next one...