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Hello all, I am in the process of dismantling an engine for rebuilding. Engine is still on frame, and got front PTO, bearing & basket pulley off; drive shaft disconnected.

I was able to loosen the lock pipe nut that helps keep the exhaust manifold secured to engine head. However, how in the world does one remove a seized iron exhaust manifold (curved iron pipe) that is threaded into the aluminum head, without wrecking either one? (Would anti-seize during reassembly last?)

Since I will be re-using that head, perhaps it can be machined with that piece of iron remaining in place? Why fight to take it off if there's no benefit to doing so...?!

I would prefer installing a new flange-type manifold though, with a short straight stub instead. (I'm assuming the head can be drilled and tapped for two bolts there.)

Thank-you in advance,

I have always gotten the threaded nipple or street elbow to un-thread from the block. I do run 1" pipe tap to clean up the threads as they get filled up with carbon behind the fitting. I do use anti-seize and Teflon tape.
I have never worked on the the aluminum heads but if the aluminum becomes gaulded to the steel pipe the head may not be able to be re-tapped and you will need a new head. I would use anti-seize and Teflon tape.

PTWannaHave wrote:However, how in the world does one remove a seized iron exhaust manifold (curved iron pipe) that is threaded into the aluminum head, without wrecking either one? (Would anti-seize during reassembly last?)

The elbow "should" be threaded into the block,which is cast iron.I have removed those by heating and a BIG pipe wrench.If that does not work or you don't have access to a way to heat it I have cut them off leaving a short stub then cut through the wall of the elbow/pipe perpendicular to the threads until you can break it loose even if it comes out in pieces.Don't sweat cutting into the threads in the block.....it really won't hurt anything,just don't go crazy

X2 on Geezers recommendation to chase the threads.I buy taps that size at the (don't look BB)pawn shop.

You guys are loosing me If this is the pipe in question I'd leave the thing alone, why take it out?

i'll agree with that leave it alone

Klapatta wrote:You guys are loosing me If this is the pipe in question I'd leave the thing alone, why take it out?

Hello Klapatta,

I have two reasons for wanting to remove the identified pipe:

• 1. thought it would get in the way of machinining for rebuilding purposes
  2. would prefer a flanged straight stub as I do not necessarily want the rest of the exhaust in front of engine (stock configuration). A flanged stub would hopefully make life easier in a future disassembly...?!

I may have erroneously thought that the iron pipe was threaded into the 'aluminum head' when it might be in the 'iron block'. This is a 14hp 147 engine, which may, or may not be the original engine.

Thanks for the other tips provided!

I suppose I should also consider having the machine shop (who will prep surfaces for rebuilding) remove that elbow for me...

Bye for now,

When I do a rebuild I strip the block to its barest bare.I do this for a couple of reasons.
1)I want to make sure the exhaust port and threads are not damaged or cracked.
2)I chase ALL threads before a thorough wash and dry prior to assembly.
3)so I can put a stack on it(vroom vroom )

My 1450 was deemed scrap because a p/o had left the elbow to rattle around until the threads were gone.In my normal rednecked way I made a flange and welded a piece of pipe to the flange to make a bolt on elbow.......and now I have a dual hyd Cub with nice original paint and a low hour replacement engine for cheeeeep.

Sounds like Mike has a QL, EWWWWWWWWWWWWW

Nice redneck fix!

I'm assuming the machine is a 125 from after reading your related thread. It ought to have the steel style pipe as posted in my previous pic then.
The Quiet line machines are fitted with a pipe such as this and are made from cast iron. These are far easier to remove than the steel pipe type due to it's OD straight cut thread. The steel ones are fitted with a taper cut thread and wow can they get seized in. The cast iron ones when stuck or snapped off can be chipped away and broken out in pieces, but the steel type cannot.
If your considering in noise reduction as one of your factors, in my opinion a stack as had been mentioned is not the way to go. That will (1.) change the noise location from one foot in front of your right knee to two feet in front of your ear drums. (2.) That also changes the location of your carbon monoxide emissions from the ground to the path of your nose. No thank you, I quit smokin a while back
Obviously, I'm not a huge fan of stacks but they are great for other people's tractors
More often than not when removing the steel type pipe it will become greatly distorted from wrenching and it becomes no longer usable. That's worth considering.
I have bought tractors for less than what that pipe costs.
Another thing worth mentioning- there are no serviceable parts inside that port hole other than the valve guide. Any carbon removal can be done at the exhaust port after the valve has been removed with a shotgun brush.

Great insight, thanks!

While the engine was on the (automotive) engine stand, I finally managed to get that darn exhaust pipe off the block... I put a pipe wrench on it, had one hand on the pipe wrench and the other hand hitting the tip of the pipe with a small sledge hammer.