DamnHippie
02-23-2007, 06:21 AM
This is the kind of thing that changes an engine swap from a 3-day job to a 2-week deathmarch.
The exhaust manifolds connect to the catalytic converters with 3 studs and nuts on each side. When we were removing them, 4 came out clean (the nuts were rusted to the studs, but the studs came out just fine). One stud snapped off flush with the flange on the cat, and on the other side one nut came off and left the stud behind, but the nut took most of the threads with it as it came off.
I tried to get the remaining stud out by welding a nut to it and carefully using a breaker bar to work the stud back and forth in the hole to crumble the rust or whatever was binding it. It would turn back and forth a couple degrees with an awful squeak, but then it snapped flush with the flange.
I tried all the usual things for getting stuck bolts out. I sprayed Blaster on them for days. I drilled the center and tried using an "easy out". I tried a torch then more easy-out action. Nothing worked. On one side I had to drill the whole stud out, and in the process ate enough of the threads that a right-sized stud is never going back in there. On the other side I've got the stud 95% drilled out, but there's still a thin sheath of stud protecting/hiding the threads. I doubt it's gonna come out without ruining the threads and oversizing that hole too.
So... why are these exhaust parts held together with studs and nuts instead of through-bolts and nuts in the first place? You can get to both sides, so a bolt and nut seems like it would work fine, unless there's something special about exhausts I don't know. (I'm pretty ignorant about exhaust stuff.)
I have two potential routes from here, I think:
- Drill the hole from M10 to M12 size, re-tap it, and use oversized studs.
- Use a through-bolt and nut.
I'd like to go with the latter, because it doesn't require drilling larger holes in the exhaust manifold flange to fit larger studs. But if there's some good engineering reason to use a stud, I'll do it the hard way.
I've already spent 7+ hours on extracting these two studs. Not exactly a deathmarch, but it sure is sapping my energy for the whole project.
The exhaust manifolds connect to the catalytic converters with 3 studs and nuts on each side. When we were removing them, 4 came out clean (the nuts were rusted to the studs, but the studs came out just fine). One stud snapped off flush with the flange on the cat, and on the other side one nut came off and left the stud behind, but the nut took most of the threads with it as it came off.
I tried to get the remaining stud out by welding a nut to it and carefully using a breaker bar to work the stud back and forth in the hole to crumble the rust or whatever was binding it. It would turn back and forth a couple degrees with an awful squeak, but then it snapped flush with the flange.
I tried all the usual things for getting stuck bolts out. I sprayed Blaster on them for days. I drilled the center and tried using an "easy out". I tried a torch then more easy-out action. Nothing worked. On one side I had to drill the whole stud out, and in the process ate enough of the threads that a right-sized stud is never going back in there. On the other side I've got the stud 95% drilled out, but there's still a thin sheath of stud protecting/hiding the threads. I doubt it's gonna come out without ruining the threads and oversizing that hole too.
So... why are these exhaust parts held together with studs and nuts instead of through-bolts and nuts in the first place? You can get to both sides, so a bolt and nut seems like it would work fine, unless there's something special about exhausts I don't know. (I'm pretty ignorant about exhaust stuff.)
I have two potential routes from here, I think:
- Drill the hole from M10 to M12 size, re-tap it, and use oversized studs.
- Use a through-bolt and nut.
I'd like to go with the latter, because it doesn't require drilling larger holes in the exhaust manifold flange to fit larger studs. But if there's some good engineering reason to use a stud, I'll do it the hard way.
I've already spent 7+ hours on extracting these two studs. Not exactly a deathmarch, but it sure is sapping my energy for the whole project.