Head Threads Stripped at Exhaust Manifold

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meatloaf

meatloaf

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So my son decided to change out leaky exhaust manifold gasket... In the process of putting it back in, 5 of the threads were no longer holding the bolt, I could slide the bolts in and out. We tried some cheap Autozone helicoils & they would not tighten and came out. So we tapped these to 12mm x 1.75 and these stripped again. Are there any alternatives? I do not want to swap the head at this time...

Truck = 92, 22RE

Thanks in advance,
ML
 
ouch.
maybe a coarse thread would work better.
I've got nothing if helicoils and upsizing the bolt did not work. You're not overtorquing the bolts?
I wonder if a high temp threadlocker like Rockset would help in this particular application.
 
Devilmans Hand said:
ouch.
maybe a coarse thread would work better.
I've got nothing if helicoils and upsizing the bolt did not work. You're not overtorquing the bolts?
I wonder if a high temp threadlocker like Rockset would help in this particular application.
Click to expand...

Thanks for the reply Devimans Hand,

i am going to try coarse thread bolts. as for over-torquing, good question, i did notice that when my son was tightening the bolts, he put a lot more effort on the bolts closer to the firewall and the gasket was/is still loose. maybe the manifold is warped???

How does the Rockset work?
 
It sounds like something is warped. I can't remember the torque, but it isn't that high. If you/he stripped the 12mm and the helicoil and it still isn't getting tight, something is wrong with one of the two surfaces I'd bet.
 
that's what I kind of figured... can the manifold be planarized at a machine shop?
 
Get a hold of Jim at Jimsgotparts.com. He had a stack of manifolds last time I was there. Probably your best bet.

As far as the striped holes...A good helicoil, the kind you tap in and use the special punch to set it would be my next avenue. The punch expands the helicoil to bed into the metal...
 
Common problem. My 22RE swap motor was the same way. You can sometimes run a tap through and put a longer stud or bolt in. It's also possible that the manifold could be cracked. That will make it not sit flush as well.
 
meatloaf said:
Sam,

what do you mean by "through", how far in?

Thanks,
Luis
Click to expand...

I don't have the specs. I think one of mine I ran a bolt that was a couple mm longer from the outside. With a new gasket and the correct torque it doesn't seem to be leaking. I VERY rarely drive mine though.
 
meatloaf said:
Thanks for the reply Devimans Hand,

i am going to try coarse thread bolts. as for over-torquing, good question, i did notice that when my son was tightening the bolts, he put a lot more effort on the bolts closer to the firewall and the gasket was/is still loose. maybe the manifold is warped???

How does the Rockset work?
Click to expand...

Rockset is similar to loc-tite but is used on firearm barrels and designed to operate at those temperatures. Where red loc-tite will melt, rockset will hold solid.

sounds like the manifold is warped like others have stated.
 
meatloaf said:
So we tapped these to 12mm x 1.75 and these stripped again.
Click to expand...

FYI gents, 12mm x 1.75 IS course thread. 12mm x 1.25 would be the fine thread option. 12mm x 1.5 is the same as your wheel studs. Usually the Helicoils/Recoils work fine.

Yes, exhaust manifolds can be machined flat. Might be time for a header.
 
As others have said, common problem on these trucks.

I replaced mine with studs, after the machine shop coiled 4 of the studs for me... and I had to coil another one on my own. The studs are locktite'd in.. also, I took my exhaust manifold to a machine shop to get the surface flat again. No leaks to date.
 
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