Big Block Frozen Exhaust Bolts

[KS2506]

Trying to remove the exhaust bolts from the right side manifold that hold the exhaust pipe to it. Have been soaking in PB blaster for a week. Problem is that I can only get the stuff on the end of the bolt and nut. Used an air impact tool today and could not budge them. Any suggestions for removal without breaking them off. Engine is in the vehicle so can not use a torch to heat them. Also tried Kroil with no luck.

 

[bucket]

You can use a torch, you just have to be careful. Otherwise I've found it's easiest to just break them off, remove the manifold and replace the studs with it on the workbench.

 

[legopnuematic]

Problem solved.

You must be registered for see images attach

 

[bucket]

I forgot I had pictures. Look how easy it is to deal with the head pipe bolts when the manifold is off:

You must be registered for see images attach

You must be registered for see images attach

 

[SirRobyn0]

Honestly I've done a lot of exhaust work through the years and stuck flange bolts are a worst nightmare in my opinion. If you can still see the treads on the studs you maybe able to work them off, if you can't make out the treads from the rust there is little you can do to save them. You have soaked them in PB that's great, after a week the penetrating oil has done all the penetrating it can. If you have access to a torch and feel comfortable you can heat those bolts up safely, heat them until they are red hot and they should come right off. If you don't have a touch or are uncomfortable using it where you need to start the engine and run it until the exhaust is good and hot, then try to break them loose. Of course it's real easy to burn yourself doing that but it might do the trick. You can try getting them hot with the touch or by running it and then shooting some cold water on the studs, this is risky if you get to much cold water on the manifolds as you might crack the manifolds, but getting the studs hot and then quickly cooling them can break the rust free. That's all I've got. Often times it ends up being easier to break the studs and deal with drilling out the studs than it is to save them. I'm not sure what the overall project here is but another option is to cut the pipes below the flange and then weld the new pipes in, of course that doesn't work if you have leaky flanges. Good luck, I know all to well how awful a project like this can be.

 

[ali_c20]

I would choose the break them and replace them method...

 

[Poppy 87]

I forgot I had pictures. Look how easy it is to deal with the head pipe bolts when the manifold is off:

You must be registered for see images attach

You must be registered for see images attach

I did mine (right side) this way and found a crack in the manifold that could not be seen while attached to engine

 

[Catbox]

I did mine (right side) this way and found a crack in the manifold that could not be seen while attached to engine

We just had this same thing on our big block.
Fortunately the spare big block that came from the junkyard had the correct side for us to simply replace it with an un-cracked piece.

 

[bucket]

I did mine (right side) this way and found a crack in the manifold that could not be seen while attached to engine

Lol, me too. I put it back in anyway, I still can't hear it

 

[Craig Nedrow]

I have literally removed thousands as a machinist. Use a 60 degree center punch and if on the first try, the hole is not centered, just angle the punch till it looks good, then give it one more hammer hit parallel with the stud. 3/8 16 tap drill is 5/16 for about 75% thread. Use a center drill to get the hole started if you have one. If not use a 1/8-3/16 drill and try to keep the drill in the center. If it is off some, no big deal, just don't get into the threads. use a spiral type easy out, and see if it backs out. If not continue to use a larger drill until max of .3125 (5/16). you can pick the slivers out that are left in the old threads. If the threads are toast, use a stainless helicoil, or drill out for a Keensert, either can be purchased at a fastener/bolt outlet. Yes I usually did this on a Bridgeport mill, but have done many by hand. sharpen your drill and make sure lands are the same width and angle. Or use a new drill. I sharpen all my drills, it is an acquired skill, but one that is easily learned with practice.

 

[Salty Crusty]

If you're still working on this, my old machinist used a propane torch and some wax. Heat the stud/bolt, then hit it with wax. The wax is supposedly drawn into the tiny space between the threads and helps lubricate 'em.