Removing Rusted Exhaust Nipple in Kohler

[JoeM 7,874]

I was working on an old Kohler and the PO installed a pipe nipple and sprinkler head muffler. Wanting to change the configuration, I set out to remove the old nipple and found mother natures Loctite, (rust), was used. I have had these in the past and most come out with a big pipe wrench, but this one was not go. It was so tight the nipple was distorted.

I removed the last one like this by cutting the nipple off within a 1/4" of the block and used a loose hacksaw blade to cut through the side wall of the nipple, in two places, until I nicked the threads. If you have a good blade, it cuts fairly easy. Then bump in the piece and removed the nipple, Tapped the thread and it worked out okay.

I figure there are others that had this issue and I am sure there are other ways, possibly easer.

It is just simply amazing how that rust can hold on and make metal stick.

I included a few pics.

 

[Digger 66 3,485]

I would  suggest a left handed tap slightly larger than the I.D. of the nipple material .

Before I tried anything though , I would tip the engine ( or the whole tractor if need be ) toward the piston and soak it with some concoction for a few days .

But it looks like you did a fine job ! 

 

 

 

 

 

 

Edited November 24, 2019 by Digger 66

[Mikey the Monkey 697]

nice way to do it...what is the tap i need when searching online for one?

[ebinmaine 67,683]

I've used a similar method on the 16 in Cinnamon Horse and a 12.

Time consuming and requires patience but works well.

 

 

[adsm08 2,087]

When replacing the muffler on my K181S earlier this year I ran into a similar issue. Not only did I distort the pipe (but not the threads) I managed to lift the whole front end of the tractor off the ground by that pipe.

 

Then I tried to tighten it, and it moved in just fine. Came out really nicely after that too.

[gwest_ca-(File Mod) 11,050]

29 minutes ago, Mikey the Monkey said:

nice way to do it...what is the tap i need when searching online for one?

Pipe sizes can be deceiving

1/2" pipe is .840" OD (approx 27/32")

3/4" pipe is 1.050" OD (approx 1-3/64")

1" pipe is 1.315" OD (approx 1-5/16")

1-1/4" pipe is 1.660" OD (approx 1-21/32")

 

Pipe taps can be expensive. Places like Harbor Freight may have a set reasonably priced and good enough for cleaning up rusty blocks.

 

A trick I learned from a servicing dealer 60 years ago. Clean up the threads. Apply Never Seize to the male and female threads. Add an electrical conduit lock nut to the male threads as far as it will go by hand.

Insert the male threads in the block by hand as far as it will go. Back it off 1/2 turn. Now tap the lock nut with hammer and punch to tighten the assembly to the block and maintaining that 1/2 turn out.

This procedure was repeated spring and/or fall as they were servicing equipment for the next season. It works - they never have a chance to seize.

 

Garry

[JoeM 7,874]

Yep Gary it, It is 1 inch NPT, home cheap o

 

[squonk 41,164]

32 minutes ago, MrOiluj52 said:

Yep Gary it, It is 1 inch NPT, home cheap o

 

That's a heck of a price for a 1"tap. They are usually $100!!! 

[ebinmaine 67,683]

59 minutes ago, adsm08 said:

Then I tried to tighten it, and it moved in just fine

Here in the road salted Northeast and especially near the ocean... We have huge and constant issues with rust.

 

I learned a neat trick from a tech awhile back.

 

You can almost always TIGHTEN something but you CAN'T always LOOSEN that same thing.

 

 

One of his most simple and best ways to defeat corrosion was to tighten a bolt just a few degrees, then loosen. Repeat.

 

 

 

[ebinmaine 67,683]

1 minute ago, squonk said:

That's a heck of a price for a 1"tap. They are usually $100!!! 

They're cheap for sure.

And they actually work pretty well...

Maybe not for constant shop usage but great for occasional help.

 

Cutting oil is a must.

I've found the hard way that they're a bit brittle.

 

[JCM 9,196]

Removing that nipple reminds me of removing rotted nipples on Steam Boilers , Supply and Return Headers etc. That process has always worked for me, although glad I don't do much of that anymore. I have a set of Ridgid Taps from  1/8''  to  2'' that i bought  38 years ago, can't remember the cost but they were very pricey, but I still have all of them and they have never failed me.

[peter lena 8,644]

agree with members on this issue, my experience working with a pipe-fitter, taught me to use a solid leverage point to move just about anything. using the existing exhaust nipple as your starting point , you must detail and enhance the  initial impact drive. i use an  18 or 24" pipe wrench tightly secured at nipple to engine block area angled up to enhance your down ward impact with a 3 lb hammer. there should be  NO HAMMER BOUNCE ,  JUST A SOLID IMPACT DRIVE, that will start the movement. penetrating oil helps , but its the solid , no bounce impact that will move that nipple, pete

[pacer 3,174]

I'm having a hard time seeing how a tap helps in this situation -- adding threads to the nipple does what??

 

I just grab my variable speed jig saw with a metal blade and cut through the threads at 2 points and the nipple will almost fall out.

[Digger 66 3,485]

12 minutes ago, pacer said:

I'm having a hard time seeing how a tap helps in this situation -- adding threads to the nipple does what??

 

 

 

They're using the tap to chase the existing threads after the nipple material has been removed .

[stevasaurus 22,765]

I just cut the nipple so about 1/4" was sticking out, then, with a cold chisel collapsed what was left of the nipple in the block.  It collapsed easily and then pulled out.  Re-tapped the threads with a sacrificial nipple.  I'm frugal.  

 

 

 

[squonk 41,164]

Back in the day when I could actually see, I used a cutting torch to slice the inside of the nipple. 

[Achto 27,614]

Another trick that has worked well for me. Before you try to loosen the pipe smack it a few good times with a hammer. Not so hard as to crack the engine casting but some good whacks. This jars the rust & will help the threads break loose from years of brown weld. I learned this trick from a pipe fitter & it has worked every time for me.

[cafoose 3,355]

42 minutes ago, Achto said:

Another trick that has worked well for me. Before you try to loosen the pipe smack it a few good times with a hammer. Not so hard as to crack the engine casting but some good whacks. This jars the rust & will help the threads break loose from years of brown weld. I learned this trick from a pipe fitter & it has worked every time for me.

Maybe use something like this on an air hammer?

[Achto 27,614]

9 minutes ago, cafoose said:

Maybe use something like this on an air hammer?

 

This does work most excellently and I do use it. But not all have the luxury of air tools. Figured every one would have a hammer though.

[adsm08 2,087]

11 hours ago, squonk said:

That's a heck of a price for a 1"tap. They are usually $100!!! 

 

There is a surplus store around me where I can buy taps 3/4"-2" for $18/lb.

[Mudrig150 298]

I got mine out by totally intentionally breaking it off almost flush with the block. Soaked it for 2 weeks and with only a tiny bit of force it just let go (and not in the way I wanted). I then used a pry bar like a chisel and chiseled the 2 cuts out, knocked out the cut, and used the hammer to knock the rest out.

[Kelsey 91]

After following this thread's instructions, our K241's threaded nipple came out in less than 12 minutes.

Thanks to all !!

Kelsey