Cycledude
Well-Known Member
Just buy a different head, yes it’s expensive but then it will be properly fixed and you won’t wind up doing the repair more than three times.
Head replacement. Engine in or out?
- Thread starter andrew_donaldson1
- Start date
scott123007
Well-Known Member
I think a mountain is being made out of a mole hill. Just get some Permatex High Temperature thread sealant, put it on the stud, and call it a day. It's good to 400 degrees. If you don't feel that is enough, you can use some JB Weld extreme heat metallic paste. Put a dab on the tip of the stud and coat the threads with that and screw it in. Since you have a pin hole in there already, it should screw right in without causing a high pressure air pocket. Good to 1000 degrees 
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andrew_donaldson1
New Member
That's a good idea. A dab of JB weld on the end of the grub screw would also hold the weld in place to cure.
Tenman
Well-Known Member
I think I would try Teflon first just to see if it would work. Quick and easy but it might burn out. Google says 500F
blitz11
Well-Known Member
I bought some used BMW/5 heads off of ebay. Seller packed them like crap. Dented the hemi combustion chamber. Took my dremel tool, and then smoothed the head with a sanding wheel, then filled the "holes" with JB weld (really cleaned it up).
Reassembled, then ran it for a month. Pulled a head, and the JB weld was still there. The 600's detonated like crazy, but the jb weld held.
My daughter's KTM EXC had the a replated cylinder, and there was a small pin hole leak from the cooling channel into the exhaust port. Smoked white, and used coolant.
Made a pressure test rig, found the leak while the cylinder was submerged, and once dry, covered cooling channel with JB weld (not the qwik, but the standard).
She rode that bike 15 years without a bit of leakage.
You'll be fine if you do this.
1. put a bit of JB weld in the hole. Give it plenty of time to set up, and make sure that the new stud doesn't contact that JB weld.
2. Use red stud mount loctite on the threads to seal the threads and hold the stud (see post above). Don't use teflon tape - that stuff is slippery, which is what you DON'T want.
Reassemble with never-seize on the exposed threads. That way you won't have to back out the stud ever.
Ride the p!ss out of it.
Reassembled, then ran it for a month. Pulled a head, and the JB weld was still there. The 600's detonated like crazy, but the jb weld held.
My daughter's KTM EXC had the a replated cylinder, and there was a small pin hole leak from the cooling channel into the exhaust port. Smoked white, and used coolant.
Made a pressure test rig, found the leak while the cylinder was submerged, and once dry, covered cooling channel with JB weld (not the qwik, but the standard).
She rode that bike 15 years without a bit of leakage.
You'll be fine if you do this.
1. put a bit of JB weld in the hole. Give it plenty of time to set up, and make sure that the new stud doesn't contact that JB weld.
2. Use red stud mount loctite on the threads to seal the threads and hold the stud (see post above). Don't use teflon tape - that stuff is slippery, which is what you DON'T want.
Reassemble with never-seize on the exposed threads. That way you won't have to back out the stud ever.
Ride the p!ss out of it.
andrew_donaldson1
New Member
Great thanks. Can i ask why the new exhaust stud couldn't touch JB weld once its set?
Keen to torque the stud down to spec you see...
RCinNC
Well-Known Member
If you torque down too hard with a metal stud onto a relatively thin layer of JB Weld, you might crack it and lose the seal on the hole.
andrew_donaldson1
New Member
I see. Appreciate your help.
Tenforeplay
Well-Known Member
I wouldn't torque the stud, just insert it with the sealant. The only reason to torque the stud would be to keep it from backing out, that would have to be more than spec'd for the nut which is something like 20 lbs or nm. Using studs on engine blocks I've never torqued them, just insert with antiseize, use 80 lbs on the nuts and the studs never come out when the nuts are removed. But if your's does come out, just reinstall with sealant. KISS
andrew_donaldson1
New Member
Thanks for everyone's help. For continuity of the thread, here's what i did based on the above advice. After an overnight water test and a heat cycle today seems to have worked:-
Put a small amount of Jb well high heat on the flat end of a 7mm drill and pressed it into the bottom of the hole and padded it out.
I waiting for an hour and put a tiny additional layer on top using same method.
Then left overnight to test if it was water tight and it was. Great.
Then today i put a dollop of jb weld high temp gasket sealant into the bottom of the hole and also on the new stud thread and then inserted the stud to finger tight only.
Left for an hour, reconnected the exhaust and ran an engine cycle through and no leaks so far. Will monitor over coming weeks but seems like a fix thankfully saving me a few hundred quid.
Thanks everyone.
Put a small amount of Jb well high heat on the flat end of a 7mm drill and pressed it into the bottom of the hole and padded it out.
I waiting for an hour and put a tiny additional layer on top using same method.
Then left overnight to test if it was water tight and it was. Great.
Then today i put a dollop of jb weld high temp gasket sealant into the bottom of the hole and also on the new stud thread and then inserted the stud to finger tight only.
Left for an hour, reconnected the exhaust and ran an engine cycle through and no leaks so far. Will monitor over coming weeks but seems like a fix thankfully saving me a few hundred quid.
Thanks everyone.