View Full Version : Broken Exhaust Bolts - machinist or exhaust shop?

11-17-2006, 05:59 AM
i'm in broken bolt hell right now.

i have a Pontiac 389 that has a lot of miles on it, and on of the exhaust manifolds actually cracked in half. i have the motor out right now to fix a couple other items on it. wouldn't you know, that on that side of the motor, there were 4 bolts that broke - even with heat applied, and PB blaster soakage. other side was fine, makes me wonder why one side (drivers) would have so much more problems.

anyhow, i've given up on trying to extract them myself. in fact, i wonder if i even buggered up on of the holes while trying.

so, i'm going to just take the head off and take it to a pro. but i'm wondering if i should take it to a machinist or exhaust shop?

11-17-2006, 06:41 AM
They will come out if you can apply enough heat. A propane torch won't do it. An oxy- acetalene will. Just heat up the whole area as hot as you dare. Let it cool some, then spray some lube. You'll probably have to do each hole a couple times. FRANK

11-17-2006, 09:31 AM
I would take it to a machine shop !

11-17-2006, 10:02 AM
'chine shop. I wouldn't trust an exhaust shop.

11-17-2006, 10:09 AM
There are places that use lazers to cut them out VERY cleanly.
Ive posted a bunch of times how to extract broken bolts that never fails.
Try a search on broken bolts sift through and find my replys.
If you dont have a mig welder than dont bother just find a guy that does lazer cutting its very economical as well.

We have a guy out here that does it very cheap, somthing like that would cost us about 45 bucks

11-17-2006, 01:21 PM
i just called the machinist that is doing some other motor for me. when i told him that a couple of the bolts are alread buggered by my attempt (below the surface), he said he could not do it, that it needs to go to someone with a large EDM machine. ?. he said it gets submersed in oil and hit with a carbonite arc. he did not know who has one in town and did not suggest a solution.

i do not have an OA torch, and i'm not comfortable getting close to the head with a welder (much less the buried bolts).

what is the technique called with the lasers?

thanks. ugh.

11-17-2006, 01:29 PM
I think when they say Laser they are refering to the EDM method.

11-17-2006, 01:43 PM
making progress... i found a guy with an EDM machine and he said he could do it. i told him i buggered one up pretty good and he didn't flinch. said no prob. can't wait to see this machine.

stupid thing is that this is from a motor that i just want to keep running. it's just that the cracked exhaust manifold was so bad that it had to be replaced. so for a motor that is really not worth much effort, i have it out of the car and torn down to a head removal just to fix the exhaust leak.

11-18-2006, 07:48 AM
Too bad! :(

11-18-2006, 10:37 AM
EDM is just a big controlled electric arc to erode away the metal. The harder the metal the faster it cuts.

For bolt removal EDM can be very good and it wont' matter how buggered as the carbon electrode will never touch the head, it is the electric sparks between the carbon and head that erode away the bolt to dust but in a very controlled manner.