Help! Helicoiled my head and the studs keep backing out!!!

[MarkIII4Me]

First off, the engine is out of the vehicle. The thing is completely rebuilt and I had to helicoil both the intake and exhaust side due to the threads striping when the manifolds were removed. I screwed brand new studs from Toyota into both the intake and exhaust sides of the head. The lower intake mani went on just fine, but the exhaust mani didn't. With a torque wrench I torqued the nut on the first couple of studs to the recommended 29ft lbs. However, when I got to the third stud from the left, it started backing out. Same happened for the next 3 studs I tried. The helicoils are staying put, but the studs back out. Maybe the oil I used to screw in the helicoils is lubricating the studs?

Anyways, my buddy talked me into putting some jb weld around the studs, but that didn't work either. Probably was a stupid idea to begin with :3d_frown:. Maybe it's a good thing it didn't hold. I haven't pulled the studs that had the JB weld completely out yet, so I don't know if it's pulling the helicoils out or not. I doubt it is. So what to do now? I was thinking of just using bolts instead of studs.

What can I put on the bolts and the nuts that go on the studs to the turbo to keep them from getting loose over time (I'll be running 25psi of boost). Lock washers? High temp lock tight?

Thoughts?

 

[benchwarmer]

I don't think you're supposed to lubricate heli-coils when you install them. At least I never have. At any rate, if the coil themselves are holding I would just use some high temp Loctite and never worry about it again.

 

[MarkIII4Me]

I haven't been able to find any hightemp loctite. Also, I tried using JB weld and that didn't even hold to a measly 29ftlbs. WTF?!!

 

[HommerSimpson]

if the helicoils were taped with right tap and the right helicoils were installed... but the stud is pulling out of the helicoil? then its the wrong size stud for what ever size helicoil you installed

 

[MarkIII4Me]

10x1.25 Helicoil kit from Autozone.

And I bought new studs directly from Toyota.


3 studs bite and stay. 4 studs don't. I just don't get it :cry:.


Wait, how important is it to use the actual Toyota nuts? 2 studs that are staying are using original nuts, 1 that is staying is using autozone nuts. The 4 that are working loose are all using autozone nuts. Could that be the culprit. Honestly tho, no matter how crappy the nuts, not holding to 29ftlbs?

 

[Scot]

10x1.25 Helicoil kit from Autozone.

And I bought new studs directly from Toyota.


3 studs bite and stay. 4 studs don't. I just don't get it :cry:.


Wait, how important is it to use the actual Toyota nuts? 2 studs that are staying are using original nuts, 1 that is staying is using autozone nuts. The 4 that are working loose are all using autozone nuts. Could that be the culprit. Honestly tho, no matter how crappy the nuts, not holding to 29ftlbs?

Check out the oversized stud kit from driftmotion....

 

[supramk3man]

Agreed while the motor is out try to fix it right. Order the oversized studs i had something like that happen with a build and put the bigger studs in and it tighted up nicely.

 

[simpsons7s]

+1 on the oversized kit from driftmotion. I had the same problem and it fixed it.

 

[jdub]

Did you have the head hardness tested?

 

[MarkIII4Me]

Crap! Now I find that due to the application of JB Weld, the coils are now coming out with the studs. So now I have 3 completely stripped holes. I guess I'll just got a stud size up and helicoil.

Will that driftmotion kit work for me in this case. I can't remember the size of the bit needed to drill the holes out in the first place. I hope there's still room to bore it out for the bigger helicoils.

 

[IJ.]

Just replied over on SF

So the original drilled/tapped hole for the Coil was too big/sloppy.

Have a look for "KeenSerts" they're a thickwall repair so you can keep the stock studs and using locking pins so they can't back out.

Bad news is usually when the Studs strip/pull threads it indicates that the head is annealed (soft)

 

[Jaguar_5]

Yes, go with the driftmotion kit, install it correctly, problem solved. (if your head hasn't annealed)