Broken exhast pipe. 8hp Kohler
 

I have a Cub 800 (hence the screen name) and today while pulling a lawn roller around it started popping, shut it off and discovered that the exhaust pipe had broken off where it exits the cylinder. maybe about 1/8 " sticking out. not enough to get a pipe wrench on. I doubt if this was ever removed.
What is the easiest way to get this stub out? I would prefer not to remove the engine right now. Is the pipe a regular pipe thread? or something special?

I haven't started taking anything apart yet but it is mostly original. I think the stock muffler.

My thought was to get in there with a hacksaw blade and try to cut through what is left of the pipe.

I don't have an oxy/acet torch so that is out. Probably couldn't get it red hot just with mapp gas.

I'm sure this has happened to others, what did you guys do?

Heating the pipe wouldn't help. It would just make it tighter.
If it was mine, I'd get a smaller pipe and weld it to it, then unscrew it. Then no threads are damaged. That block is rare, I wouldn't do anything to it to risk damaging the threads.... if it leaks with a new pipe your screwed. If you don't have a welder, I'd take it to someone who does.

If you cut it into 4 pieces with a hacksaw that might work...... just don't damage threads in the block. After cutting the pipe stop and try to break it with a hammer and punch.

Cub 800 since you have the unit that you do, it has a pretty substantial muffler that hangs off the front of the block inside the shrouding. After your repair make sure the muffler bracket that resides on the right side is in tact and the bolt is there to hold it in place or this may happen again. It might be just something that happened but take a close look to make sure. Also a good idea is to put one of the conduit nuts on the pipe and jam it with the pipe and block so it won't get loose, good luck

I have removed many broken off pipes using a hammer and chisel, starting from the "free end" tap the end of the pipe directly toward the center as though you were going to split the pipe from one end to the other, but just tap it in, don't try to cut it through.

Keep working it in, most times the pipe will begin to cave in on itself and get very loose in the hole.

I've done exactly the same as Sam has on a k321. Not as difficult as you'd think to remove.

Thanks, I may have to try it this way. I have a good welder but my skills are still developing.

And I was worrying about damaging the threads by cutting it with a hacksaw blade. .. Hammer and chisel.... I can handle that.

Next.. is this a regular pipe thread? Can I just get a piece of black pipe from the hardware store to replace it with, or is it a special piece.

Yes, it is pipe thread.


The guys who are saying they used a chisel may have been doing it with the larger engines that use a cast iron elbow. The cast will break much easier. The 800 uses a piece of pipe, not a cast elbow. I doubt without cutting it you will be able to chisel it out.

I've done a couple by as you mentioned cutting the inside of the pipe. What I did was to make 2 cuts on the inside but not deep enough to get into the threads in the block, then took a chisel and collapsed the pipe into itself. That and plenty of PB. Worked for me, your results may vary.

Just remembering you mentioned you have mapp gas, it might make what is left of the nipple softer and easier to crush into the center with chisel.
Being me, I would use a Ace/oxy to get it out, been real lucky doing it that way.
Many times on exhaust studs, I heat the manifold up and use bees wax on the stud allowing them to turn out.
But each problem presents a different approach as we all know.

I've done this on PIPE all my life and I don't ever remember a time that it didn't work out well.

In this case, a chisel that is dull will most likely work better than a sharp one.