Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp

   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp #1  

Frank Sorbello

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Jul 12, 2011
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362
Tractor
Power Trac PT-422
What are your thoughts on this? Since Power Trac will not sell a new PT-425 with a Kohler engine, I was playing with the idea of changing out my 22hp Subaru to a 25hp Kohler.

I have seen online a few sites where 25hp Kohlers are under $2000.

With the current setup on my 1999 PT-422, I have a hydraulic pump in the front of the motor and one behind it. I am pretty sure that will be a problem, as well as hydraulic hoses lengths will change, relocating gas tank and battery.

Is it worth it?


Thanks
Frank
 
   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp #2  
What are your thoughts on this? Since Power Trac will not sell a new PT-425 with a Kohler engine, I was playing with the idea of changing out my 22hp Subaru to a 25hp Kohler. I have seen online a few sites where 25hp Kohlers are under $2000. With the current setup on my 1999 PT-422, I have a hydraulic pump in the front of the motor and one behind it. I am pretty sure that will be a problem, as well as hydraulic hoses lengths will change, relocating gas tank and battery. Is it worth it? Thanks Frank
I love the 25 commands,I say if you do it, I'd also consider the 27 hp,they are almost identical but the newest versions use a big 2bbl carburator like the 30 has,I'd stay away from that setup.
 
   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp #3  
What are your thoughts on this? Since Power Trac will not sell a new PT-425 with a Kohler engine, I was playing with the idea of changing out my 22hp Subaru to a 25hp Kohler.

I have seen online a few sites where 25hp Kohlers are under $2000.

With the current setup on my 1999 PT-422, I have a hydraulic pump in the front of the motor and one behind it. I am pretty sure that will be a problem, as well as hydraulic hoses lengths will change, relocating gas tank and battery.

Is it worth it?


Thanks
Frank

I've got a 2001 model PT425 with the Kohler and my pumps are like yours. The tram pump is in front of the engine and the PTO/Steering-FEL pump is behind the engine. From my pictures...
This is the rear PTO/Steering-FEL pump on the back.

446391d1446774495-thoughts-pt-422-changing-out-pt425ptopump-jpg


This is the tram pump on the front.

446392d1446774530-thoughts-pt-422-changing-out-pt425varvolpump-jpg


Looking at the front, it appears they cut the cooling fan shroud on the Kohler and fabricated a mounting bracket for the tram pump. Can't see how its fastened to the engine.

On the rear pump, there's a mount that adapts the Kohler bolt holes to what appears to be a standard 2-bolt pump mount.

I'd imagine your's is pretty much the same way. What you'd probably have to do is make new mounting holes in the existing mounts to match the Kohler rather than the current engine. You'd also have to to shaft diameter and length measurements. But I'd guess that the hoses will have enough slack as long as you don't try to relocate pumps on either end of the engine too far. But that's all just a guess, of course.
 

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   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp #4  
My 2000 model PT 422 is using a lot of oil. So this thread is very interesting to me.
 
   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp
  • Thread Starter
#5  
New Kohler 25hp $1565
 
   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp #6  
Does the mounting bolt pattern match? I understand that if I put a new Robin engine in that I have to cut the shift shorter.
 
   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp
  • Thread Starter
#7  
Talked to Terry today. He advised to put another Subaru in it. I told him there was no way I would waste any more money on a Subaru. He then said there is some machine work that would need to be done in order for the pumps to bolt on and also would need a new engine stand. A new wire harness would be needed as well. I don't think it is going to be an easy task to change out, but it is change it out or deal with what I have now.
 
   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp
  • Thread Starter
#8  
I forgot to ask Terry, does anyone know if there is a difference in tub size between the 422 and 425?
 
   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp #9  
Talked to Terry today. He advised to put another Subaru in it. I told him there was no way I would waste any more money on a Subaru. He then said there is some machine work that would need to be done in order for the pumps to bolt on and also would need a new engine stand. A new wire harness would be needed as well. I don't think it is going to be an easy task to change out, but it is change it out or deal with what I have now.

A few shots of my older 96 1425 setup if it helps any .. Very similar with a few exceptions..
 

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   / Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp
  • Thread Starter
#10  
Thanks Barry and MossRoad. I am definitely going to do this and these pictures will help. I am going to order the engine next week. Hopefully have it completed before winter weather hits.
 
 
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