Removing 1" exhaust pipe from Kohler engine block

[ronhatch 406]

What is the best and safest way to remove the 1" stub pipe from a Kohler K-241 block?

[953 nut 58,312]

Presuming there is enough to get a pipe wrench on it; use an oxy- acetylene torch to heat the entire diameter of the pipe at the end where it meets the block red hot then turn it out with the wrench.

[JPWH 6,294]

I just recently removed one from a K181. The 1" collapsed and broke at the threads when I tried to loosen it with a pipe wrench. Then I used a small chisel  to remove the remaining pipe thread from the block.
 

[Tankman 3,520]

I've had a few where the nipple was broken off right at the block.

I carefully sabre sawed a slot inside the pipe but not deep enough to slice the block.
Then with a drift pin, tap, tap, tap on the pipe until it started to collapse, then when I was able to grap the pipe with vice grips,
turn the pipe (it was curling inward) until it collapsed enough to draw it out.

Half hour at the most. Clean the threads, vac'd out the block. All is well. 

[rmaynard 15,962]

If the pipe is still there, cut it off with a hacksaw or sawzall about 1/4" from the block. Take a small chisel and hammer and collapse the pipe toward the center. Grab it with a pair of pliers and pull it out. I've done it that way at least 4 times.

Edited August 27, 2015 by rmaynard
spelling

[Jake Kuhn 1,579]

The collapsing the nipple method works very good. But be careful doing it. I would recommend heating it and then collapsing it. I ended up cracking a block doing it once and needless to say wasn't too happy at the time. lol

[Coadster32 793]

All good methods listed here. Just do yourself a favor, and exercise some common sense. This is a touch-and go feely kind of thing.Tapping doesn't mean BFH. Slitting doesn't mean cutting thru. Heat can be good, but there might be a cost for that transferring a bunch of heat to the block. I wouldn't be surprised if you needed a new head gasket from doing this method. (they are known to go because of exhaust heat as it is.) Just take your time, go easy, and it can certainly be done.

[DennisThornton 4,771]

Lots of good advice and I think Coadster32 summed it up well.  I would try red heat first, if that fails slit the pipe with a saw and then with a small chisel and medium hammer tap from all around the outside to the center to gradually collapse as much of the pipe as you can.  Then even try to unthread the pipe with the hammer strokes.  It might not be instant but you will be able to do it with some patience.

Edited August 28, 2015 by DennisThornton
rephrased