Loose threads

[Goldenzrule]

So I am replacing my exhaust manifolds. I got all new bolts, and one of them will not tighten, the threads are stripped or shot. I tried the old bolt and that too will not tighten. I am guessing someone torqued them down to much and stripped the thread maybe. Is there anything I can do to fix this? Can the threads be retapped and use a larger thread bolt? The rest of the bolts tighten up fine. I feel like I am barely tightening them though at only 18 ft/lbs

 

[Redtruck-VA]

Helicoil should be a good fix. Becareful not to drill too deep as there is a water jacket behind the hole. I use studs on the end holes mainly just to make it easier to hang the gasket. Use might try a stud..

 

[Jason G Slabaugh]

Or you can try and re-tap the hole, but a helicoil would be good too

 

[TMyers]

Take a small dowel or pencil and stick it in the stripped hole. Mark the dowel to determine the depth of the hole. Compare the depth to your bolt length. If the hole is deep enough, you may be able to get a longer bolt to reach the undamaged threads.

If you can stud the hole, get some Loctite 620. Clean everything and apply the 620 to the threads. 620 is a retaining compound, not a thread locker.

 

[Tim Garceau]

Drill/bottom tap for a helical(8x1.25 thread 25mm long). As mentioned, depth is critical.

Any retaining compound will work one time provided you can still manage adequate torque, but if using the cast manifolds again prepare to fix it correctly soon.

We were a few days late, let us know what you decided.

 

[RonJon '06]

Take a small dowel or pencil and stick it in the stripped hole. Mark the dowel to determine the depth of the hole. Compare the depth to your bolt length. If the hole is deep enough, you may be able to get a longer bolt to reach the undamaged threads.

If you can stud the hole, get some Loctite 620. Clean everything and apply the 620 to the threads. 620 is a retaining compound, not a thread locker.

I had some stripped out holes on my '06 Hemi and ended up using exhaust manifold bolts for the 4th Gen Hemi. They're a little longer, maybe 5 or 6 extra threads and snugged up nice.