47 farmall h

When I pulled the muffler off, part of the pipe that the muffler is suppose to slide off of came with it. Very rusty. Does my exhaust manifold need replacement or major repair?

Thank you all for your help, now and in the past.

Not necessarily. Check the threads in your manifold. If they are still present and in decent shape, you may still be able to thread on a new piece after a good, thorough cleaning. It is hard to tell without seeing it though.

That pipe screws into the muffler, on threads cut into the cast manifold.

If the manifold is ok other wise you can get a tap or thread chaser and try to clean out those threads before you change the manifold.

Just so I'm clear on this; it sounds like there is a replaceable pipe between the exh manifold and the muffler?

It is a 2" NPT pipe-tap thread. A tap is going to be expensive...on the order of $250+

You can make sort of a homebrew tap for chasing the threads if you can get the extension unscrewed. Buy a 2" black pipe nipple of about 6" length. Use a die or angle grinder and slot some "flutes" into it similar to a real tap, just that they can't be as deep.

Use some sort of oil and chase the threads until you get it so the chaser turns more freely. Note the threads are tapered and won't spin as easy as a straight or bolt thread.

I'd use anti-seize on installing any new extension piece.

(quoted from post at 09:44:53 12/10/08) That pipe screws into the muffler, on threads cut into the cast manifold.

If the manifold is ok other wise you can get a tap or thread chaser and try to clean out those threads before you change the manifold.

Click to expand...

The pipe threads into the manifold, not the muffler, but I'm sure that is what you meant to say?

Many rental places will rent taps. Pluming contractors also have them. JimN in St.Cloud MN

There are two types of manifolds, gas and distillate. The typical gas manifold has about 8-10" long 2" pipe that threads into the manifold. You can get a new pipe cut and threaded at your local plumbing store. A local machine shope could clean up the threads on your manifold.

If you have the other type of distillate manifold, it has a pipe with a mounting flange. That pipe can be ordered through steiner tractor

steiner tractor

Yep, just a piece of pipe.

If the manifold is in otherwise good shape, that pipe is all you need to change out to mount your muffler.

It can be a bear to get out -- it's been subjected to water and cycles of heat and cold for a long time, so i likelyu stuck pretty good. It'll likely take some heat, some lubrication (both the chemical and the verbal varieties), but it will come out with patience and care.

I've gotten them out by clamping them in a vise, protected by blocks of wood between the body of the manifold and the vise jaws, and taking a pipe wrench to the pipe section. This is after all the heat and lubrication. I suppose you could do the same thing by laying it on the floor and holding it down with your foot while trying to wrench the pipe out. Only caution that comes to mind right off, with either method, is to do all the heating and lubing you can first, and go back for more if necessary. If that pipe is falling apart on you, it may not have enough meat left in it to take much wrenching. If it does crush/twist/break off on you, you can still use a small grinder and chisel to cut and pry away what's left.

As far as cleaning up the threads when you do get it apart, you can get a file to clean them up for a lot less than a chase or tap. 2" pipe thread is 11-1/2 threads per inch, so you need to buy a file that has that pitch. Most of them have two or four pitches on one file. What you want is one for internal threads that includes the 11-1/2 TPI. A good NAPA should have one hanging on a rack, but you may have to call a plumbing supply to find one. But we're talking something like $15-20 instead of $250, so that would be worth the effort.

Follow the link to McMaster-Carr and do a search on 2616A17 to see what the file looks like
McMAster Carr

I agree with the others.
I just go to the local hardware and buy a six inch piece of 2" blackpipe or whatever size I need and stick in. My local ace hardware has a pipe threader and threads the pipe for me and it has worked every time. He lets me borrow a thread cleaner. (Its a small town)
I have even welded some in place or used muffler putty.

5 years ago, Arnold's retapped a manifold for me. They charged for about a half hour. The manifold was removed and brought in. I used a piece of pipe i bought at fleet farm or somewhere like that.

-karl f

Yes, you need a new pipe. They are different on a All Fuel or Gas manifold. A gas manifold has a pipe that is threaded into the manifold, the all fuel pipe mounts on with 2 bolts. If yours has a Gas manifold, check the threads in the manifold and make sure they are not worn. You can get a new pipe for your manifold from Steiner.
Steiner Tractor Parts

Yes. All fuel manifolds have a cast iron pipe with 2 mounting bolts. Gas manifolds have a threaded piece of pipe.

You say, "part of the pipe" Is the bottom of the pipe still in the manifold? If so that old piece has to come out.
Remove the manifold. Lay it flat. Trim off any pipe outside the manifold 1/4 inch above the manifold Use your sawsall and cut it in two places. Go just barely into the threads Knock out the pieces. Use the 2 inch NPT tap to clean up the manifold threads. I've done half dozen, maximum 10 minute job.

Gordo