Bad or good idea to use propane torch on broken exhaust bolt?

[MarkBC]

I have a 3B and pulled the exhaust manifold off. The back lower bolt head rounded off so I had to grind off the bolt head from underneath to slide the manifold off, which was fun. Now I have this "stud" sticking out maybe 3/4". Is it a bad idea to take a propane torch to it to unseize it? Will the heat potentially warp the head?

Maybe I could weld a nut on it but access is pretty tight in there.

 

[OGBeno]

You’ll be fine.

Do it.

 

[AussieHJCruza]

You'll struggle to get enough heat into the cylinder head with a torch to warp it IMHO

 

[cruiserpilot]

My experience, taught to me by someone with experience, was to weld a nut over the stud, make sure
you get the spot dead on inside the nut, against the side. Set a couple/three spot welds with some real
heat. Generally the heat just from welding the nut to the stud will create enough expansion around
the threads for it to turn out fairly easily. Weld hot, spray immediately with a good penetrating oil,
start turning that nut before anything cools. Should work. good luck.

 

[TRAIL TAILOR]

My experience, taught to me by someone with experience, was to weld a nut over the stud, make sure
you get the spot dead on inside the nut, against the side. Set a couple/three spot welds with some real
heat. Generally the heat just from welding the nut to the stud will create enough expansion around
the threads for it to turn out fairly easily. Weld hot, spray immediately with a good penetrating oil,
start turning that nut before anything cools. Should work. good luck.

This has worked for me for decades.

J

 

[cruiserpilot]

BTW, if you are talking a little 1 lb propane torch - don't. Those are for lighting cigars and
starting campfires. Not nearly enough heat.

 

[MarkBC]

It's one of those brass Bernz-o-matic torches.

I think I'll grind off some more of the bolt so I can spin a nut on, then spin it so it's flush with the end of the bolt and I can weld the nut to the bolt right there on the end of it.

 

[AussieHJCruza]

The Bernz-O-Matic torches don't get something hot enough to achieve a great deal in my experince. If you can thread on a nut and weld it, I'd say that's the best place to start

 

[Nz Nath]

If there's anything left sticking out then you're laughing. It's when your bolt/stud is sheared recessed into the head that it becomes delicate. The heat from arc welding is immense. You might find the bolt turns so freely you could undo it by hand if it wasn't still 400c...

 

[OGBeno]

Use a MAP torch. Don’t use propane. Won’t do s***.

 

[mudgudgeon]

Use a MAP torch. Don’t use propane. Won’t do s***.

Agreed.
I've had decent results with MAP gas torch.
The main problem using it on the vehicle is shielding other stuff so you don't toast something else

 

[MarkBC]

Plumbers use that cloth behind their soldering torch for copper pipe. Or they used to before they switched to PEX.

 

[cruiserpilot]

So did you get it removed?

 

[MarkBC]

Not yet, I'm welding up 32 holes in the roof and overhauling the front 80 axle.

 

[MarkBC]

Got it. It took a few tries welding it on because the weld wasnt sticking but finally got that sob. Man that sucker was tight even after spraying it several times with pb blaster over a couple weeks and the heat from welding. And I had to finagle the grinder in there to remove excess weld to get the socket on. That's it for today, now I'm going 4x4ing in my 4runner

 

[Rusto]

Way to stick with it!

 

[MarkBC]

And I broke the 4runner. Hit a water bar. Makes a horrible rattle when I go over a pothole. I think I blew a shock out?

 

[roalco]

Tore a rear shock loose from the top bar on the floralake road from bamfield to youbou one winter.... made quite a racket... dog insisted I stop and at least wire it out of the way, it was seriously pounding under her rear seat!