PT 425 - repower options (Kohler 25hp)

[Husker34]

Well I haven't confirmed yet but I think my engine took a dump (about 1400hrs). I am looking to replace the Kohler with the same one (CH25s with a shaft on both sides) which is now a CH730/740 or possibly upgrading to the 27HP as from what I understand can possibly bolt right in (but not certain). One problem with the 27hp is all I see with those are the air cleaners/canisters that come with them won't fit in the compartment.

I also saw in a couple posts here that if I'm willing, I may be able to haul it out to Tazewell and they can repower it and potentially are pretty reasonable in price? In taking out there then I could have them just put it thru the gamut and replace or fix anything that is best done without the engine sitting in there. Thought about calling them on Monday.

Wondering if anyone has any good recommendations on what the best bang for my buck might be. Looks like a new 25hp is upper $2500's and a 27hp is pushing $3k from what I have found.

 

[MossRoad]

Definitely make the call to Tazewell and ask about options and recommendations.

Of course, same engine is easiest, least problematic, but if you can get new with more HP, fuel injection to aid in cold weather starting, etc. for not too much pain, it would be worth consideration.

 

[2manyrocks]

Doesn't hurt to price having them do it versus you putting in another engine plus it would be interesting to hear whether they think the increase in HP if the larger engine would bolt in actually translates to improved performance over the 25hp engine.

With the 30hp diesel no longer being available, I think PT is missing the boat not to at least offer a 25hp diesel option somewhere in their product line.

 

[5030]

Nice thing about all modern engines is the bolt pattern on the PTO side is universal so repowering won't be a big deal. Far as air cooled engines go, 1400 hours is usually on borrowed time today unless you are very maintenance oriented, then they will go longer but stuff like valve adjustments and clean air filtration reap time rewards. Personally, I prefer Kawasaki over Kohler but that is a personal choice with me.

 

[MossRoad]

Just to be clear, he's got a PTO shaft on both sides of the engine.

The blower housing and covers, etc., will have to be modified IF there are bolt holes for the FRONT PTO SHAFT that will have to be added as well as the FRONT PUMP MOUNT (I can't recall how that's mounted).

 

[agjones]

Several years ago, I replaced the Robin in my 425 w a Kubota 25hp.the weight, torque and fuel economy are fantastic. Added a couple of inches to the rear of the pt. Fuel tank went to the top of the engine cover. Can't stall the engine. My setup was all pumps on once side of the engine, so found a bellhousing, matched up to the pump and Kubota and gtg.

 

[m5040]

Several years ago, I replaced the Robin in my 425 w a Kubota 25hp.the weight, torque and fuel economy are fantastic. Added a couple of inches to the rear of the pt. Fuel tank went to the top of the engine cover. Can't stall the engine. My setup was all pumps on once side of the engine, so found a bellhousing, matched up to the pump and Kubota and gtg.

I have a Excell mower with a 950 Kubota waiting for the day if the 18hp goes south in my PT018. That would be a major job, but as you indicated, it will be well worth the effort.

Agjones, please let me know if you ever want to sell yours.

 

[agjones]

Lol heard, it'll be an estate sale.

 

[2manyrocks]

Did you ever post pictures of your Kubota conversion? Now I understand 425d.

 

[agjones]

Did you ever post pictures of your Kubota conversion? Now I understand 425d.

I've posted them in the past. I'll try to get more while servicing it this month.

 

[Modrob]

I’ve just discovered I’m in the same boat. (Looks like I’ll have to replace or rebuild our CH25s in the PT425. It’s about 24 years old and has done a ton of work before me. Yesterday I found it has gas in oil, one cylinder at 90psi, and the other at near 0psi. And, it still has that old, troubled coil/flywheel system. I’m thinking it’s probably more efficient to replace it, and I too am going to call Tazewell and ask about their options)

 

[m5040]

Probably the best in the long run. They are such versatile machines. If the rest of the machine is OK, it would be well worth it.

 

[m5040]

I’ve just discovered I’m in the same boat. (Looks like I’ll have to replace or rebuild our CH25s in the PT425. It’s about 24 years old and has done a ton of work before me. Yesterday I found it has gas in oil, one cylinder at 90psi, and the other at near 0psi. And, it still has that old, troubled coil/flywheel system. I’m thinking it’s probably more efficient to replace it, and I too am going to call Tazewell and ask about their options)

I guess you have a few post on this problem. One thing I would do, since you are changing the engine anyway, is to have some fun doing some quick off-the-wall repairs with the original engine. Start with checking the valve rockers under the covers to see if everything is in the ballpark and see if you can get a rudimentary check on the timing. Then gravity feed the carb with a plastic shut off in line and make sure the fuel level is higher then the carb. Put in 40W oil and try to start it again.
The negatives are that it should have attempted a start as it is now when using starting fluid, so it may have jumped time somewhere. The 40w oil might/should bring up the low side compression because the oil helps the rings to seal and gas diluted oil won't.
Might be worth a try.

 

[2manyrocks]

I replaced the Kohler v twin in my Terramite some years ago because it was the easiest route, but I've always thought a diesel engine conversion would have significantly improved its performance plus the gas engine has always seemed to use more gas than the diesel in my Yanmar 226d seems to use.

With new 25hp gas engines hovering around $2,500, a conversion to a used diesel engine might be worth considering if you could copy the conversion agjones did.

 

[Modrob]

I guess you have a few post on this problem. One thing I would do, since you are changing the engine anyway, is to have some fun doing some quick off-the-wall repairs with the original engine. Start with checking the valve rockers under the covers to see if everything is in the ballpark and see if you can get a rudimentary check on the timing. Then gravity feed the carb with a plastic shut off in line and make sure the fuel level is higher then the carb. Put in 40W oil and try to start it again.
The negatives are that it should have attempted a start as it is now when using starting fluid, so it may have jumped time somewhere. The 40w oil might/should bring up the low side compression because the oil helps the rings to seal and gas diluted oil won't.
Might be worth a try.

Oh for sure! LOL First, my curiosity is harping at me to dig in and see what has actually happened. Luckily, we don’t use it very much (I picked up a 1950 IH gas crawler/dozer several months ago that is FUN) so I have time over the winter to tear it down/replace etc. I really hoped I could rebuild it but the wife reminds me that her late husband used it heavily for years dragging out timber from our woodland, so it’s performed way beyond what was expected.
I’m anxious to call Tazewell as soon as they open back up and see what options they suggest. Even though for years I’ve usually done most projects myself, I’m a bit overwhelmed now, health-wise, aging, etc., and I have to admit it would be nice to have it done by a pro…(but I usually don’t like the more expensive tabs )

 

[5030]

Ever bother to adjust the overhead? Kohlers as well as Briggs and Scrap'em are very dependent on correct valve clearance because the compression release on both engines are actuated by an offset cam arrangement that acts on the intake valve initial clearance. Most owners never adjust the vale clearance and that equates to hard starting issues which owner blame on tother issues when, in fact, the vales are out of adjustment.

 

[5030]

Always keep in mind that these small engines (Kohler and Briggs) all have solid lifters and require adjustment (as spelled out in your owners manual, if you bother to read it)... Kawasaki as well.

 

[ponytug]

Oh for sure! LOL First, my curiosity is harping at me to dig in and see what has actually happened. Luckily, we don’t use it very much (I picked up a 1950 IH gas crawler/dozer several months ago that is FUN) so I have time over the winter to tear it down/replace etc. I really hoped I could rebuild it but the wife reminds me that her late husband used it heavily for years dragging out timber from our woodland, so it’s performed way beyond what was expected.
I’m anxious to call Tazewell as soon as they open back up and see what options they suggest. Even though for years I’ve usually done most projects myself, I’m a bit overwhelmed now, health-wise, aging, etc., and I have to admit it would be nice to have it done by a pro…(but I usually don’t like the more expensive tabs )

That 1950 IH sounds like fun! Where are you located? Hills? Mountains?

25HP diesels aren't exactly common, or cheap, but I think that it would make for an interesting tractor. But budgets, health, age, etc., do have a material impact on what is reasonable, in contrast to what might be possible...

All the best, Peter

 

[MossRoad]

The Kohler CH25 has hydraulic lifters and there is no valve adjustment. About all you can do is remove the valve cover, then check the nut that holds the rocker arms for damage/proper torque, etc.

 

[scotts562]

I have done a couple of engine swaps on PTs. It is pretty easy. Power trac can set you up with any parts you may need to adapt a new engine. Word of warning when installing the 90 degree oil drain elbow: do not overtighten or you will crack the block.

The following Kohler engine spec numbers will work. The HP ratings are per Kohler:
CH 730-3207 (23.5 hp) this one is in a 2422 with pumps on both sides of the engine
CH 730-3208 (23.5 hp)
CH 740-3363 (25 hp)
CH 730-3004 (23.5 hp) this is an old spec number but can still be used as a reference

Another spec number that may work, but I have not used is CH 750-3006 (30 hp)

When I called Kohler directly a few years ago, one of their service reps went through and identified a number of spec numbers that should work. He said they change some of the internals to get the different hp ratings, but the rest of the engine is a drop-in replacement.

Hope this helps