Bolt siezed in cast-iron manifold

[BeeKool]

This is a non Mopar ?
I have an AC WD belly mower. Muffler needs replaced.
Bolt that threads into manifold is siezed, my typical reponse is to use the blue wrench, is this a good idea or will the cast iron crack?

I do not wish to remove manifold from head, it doesnt leak and is very likely that studs may break off in head.

 

[R413]

I usually like the hot wrench. Not much meat there. You may be better off to grind off the head, then drill it out and install a heli coil. Not very hard to do and will be better than new.

 

[PP1RT]

Should be ok to heat it up some. Maybe a little at a time and let it cool slow afterwards. The bolt might let go before you get it red hot. Can you run the tractor still? Bring it up to operating temp and try the bolt before you get the torch? I have had luck with that a couple times.

 

[zyzzyx]

Why does the bolt go all the way through the casting to the other side? Is it also threaded and seized?
The bolt head can be drilled through the center with a 1/4" drill to let the threaded shank collapse when
you heat it. This will aid in removal. Make sure you center punch the head to keep the drill centered.
That long skinny eroded part goes to what? Make sure you soak it with a decent penetrating fluid as
cast iron is porous, and will help the fluid creep in.

 

[khryslerkid]

I'm thinking the muffler threads into the large hole, pipe thread.

I wouldn't worry about the bolt and just replace the muffler. Might try to locate a pipe tap to make good threads inside the hole before installing the muffler.

 

[BeeKool]

The bolt goes through to keep the stub pipe tight.
This is an old issue that Ive needed to aggress for a decade or so. Tired of running a straight pipe, want to preserve my hearing.

Its impprtant not to crack the manifold, its easily replaced but the head bolts are likely to give me trouble and that can if worms need not be opened.

I'll try a little heat.
I like the idea of drilling a small hole into the bolt

 

[zyzzyx]

Helped a neighbor overhaul an International Club Cadet engine last summer. some of the head bolts
didn't want to come loose. Had to drill two out. The hardest part was getting someone who could
overbore the cylinders for new pistons. It's not a big-block chevy, so none of the local machine shops
had the smaller tooling needed. All of the guys that used to do that type of work have retired, or died off.
Before you take too much apart, make sure there's someone near you that'll be able to help you!

 

[dryheat]

Kroil ... miracle in a can ... it has never let me down on a seized bolt. http://www.kanolabs.com/google/?gclid=EAIaIQobChMIp5eBntKM4gIV3f_jBx01PgLyEAAYASAAEgLBfvD_BwE

 

[BeeKool]

Broke it off.
Drilled it out partially, some more heat and a small chisel will hopefully do the trick.