Exhaust manifold Studs

Navajo350 · May 30, 2015

Do I need an acetylene torch to get these stubborn studs out of the block or would a butane torch be good enough? I'm not sure if butane would be hot enough, but would be easier to get than the other.

Also, I would think I have to heat up the part of the stud that's close to the block. Then, would I be risking warping the face of the exhaust port on the block. The engine is still in the tractor.

Thanks for the help.

Robert

Janicholson · May 30, 2015

Heating the stud expands it. If you try to heat it with a Butane/Propane, or even MAPP gas torch, you will be waiting a long time, and really not doing much. The addition of oxygen increases the temp to more than 5000 degrees. This will heat the stud rapidly to red hot and actually heat the block much less. The effect of this is to swell the stud and break the rust bond. You need to actually let it cool to cold before attempting to turn it. Touching a wax candle to the stud as it gets to about 200 degrees will also draw paraffin into the rust zone. DO not twist it off. Broken is much harder than complete. Jim

Steve in VA · May 30, 2015

My personal experience is to use a propane torch applied to the stud. Heat and let cool. Repeat 2 or 3 times. The heating and cooling of the slightly dissimilar metals and dramatically different heat sink will lead to separation between the two. A very, very gentle tap on the stud can help too. Good luck!

showcrop · May 30, 2015

A lot of guys swear by applying wax when hot, letting it suck in as it cools, then trying it. I have done it and the bolt came out but I don't really know if it was the wax or the oil I tried before the wax. I expect that butane would get it hot enough to suck wax in, but not so hot as to be concerned with the head. some guys swear by breaking them off then blowing the rest out of the hole with Oxy-acetylene.

David G · May 30, 2015

I really do not think a propane torch does much.

rrlund · May 30, 2015

Do you have an arc welder? Weld a nut to it close to the casting. The welding will heat the stud. Let it cool and shrink a little and it should turn out OK.

Navajo350 · May 30, 2015

Just apply heat only at the base of the stud? Or the entire stud?

Hoenes · May 30, 2015

Ditto on tapping on the ends of the studs with a hammer. Just can't get carried away since your around cast. It "shocks" the rust loose around the threads. Old timer first showed me that on old galvanized pipe fittings, such as a coupler. Hold another hammer directly across from where you're going to smack it, to absorb the hit. Almost always comes apart without twisting off the pipe threads.

jimg.allentown · May 30, 2015

The little propane/butane/MAPP torches simply do not put out the BTUs to really heat up a block, head, or even the stud. In the past, I have used oxy-acetylene with a cutting tip (not to cut, but for the BTU output) and heated the area around a stud. A few taps on the end with a small hammer also helps. Best to avoid breaking it if at all possible. Be gentle and do not apply enough force to break it off. Another thing that can help if a stud is broken off near the casting is to use a reverse sharpened drill. I have had broken bolts spin right out almost as soon as I started drilling.

BTW, it is unlikely that you would ever heat it up enough to warp a valve seat or exhaust port.

Exhaust manifold Studs

Navajo350

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Janicholson

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Steve in VA

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showcrop

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David G

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rrlund

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Navajo350

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Hoenes

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jimg.allentown

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