Re-engine a 425?

[Abitnutz]

Ok, this is all hypothetical. The engine in the PT-425 is a 25 hp Kohler Command Pro right? Kohler makes, from what I can determine, a liquid cooled version of this engine called the Aegis. This engine appears to be identical to the Command Pro except that it is liquid cooled. The bore is slightly smaller, I’m sure to handle the water jacket. The dimensions of the two engines are very close. Is there any reason why putting one of these in a PT-425 would be just too costly or difficult to be practical? I checked and the cost of the two engines is also very close. Below are the specs for both engines. It’s interesting that the LC engine has a bit more torque at a lower RPM but a lower compression ratio. Please comment…perhaps Power-Trac is listening

Liquid Cooled
MODEL LH685
MAX. POWER @ 3600 RPM
hp (kW) 25 (18.6)
DISPLACEMENT cu. in. (cc) 41.1 (674)
BORE in. (mm) 3.15 (80)
STROKE in. (mm) 2.64 (67)
PEAK TORQUE @ MAXIMUM lbs. ft. (Nm) 40.1 (NA) @ 2200
COMPRESSION RATIO 8.5:1
DRY WEIGHT lbs. (kg) 114 (51.7)
OIL CAPACITY U.S. quarts (liters) 2 (1.9)
LUBRICATION Full pressure w/full-flow filter
*DIMENSIONS
L x W x H 17.0 x 18.1 x 26

Air Cooled
MODEL CH730
MAX. POWER @ 3600 RPM
hp (kW) 25 (18.6)
DISPLACEMENT cu. in. (cc) 44.0 (725)
BORE in. (mm) 3.27 (83)
STROKE in. (mm) 2.64 (67)
PEAK TORQUE @ MAXIMUM lbs. ft. (Nm) 39.9 (54.1) @ 2800
COMPRESSION RATIO 9.0:1
DRY WEIGHT lbs. (kg) 94 (43)
OIL CAPACITY U.S. quarts (liters) 2 (1.9)
LUBRICATION Full pressure w/full-flow filter
*DIMENSIONS
L x W x H 13.8 x 17.7 x 26.5

 

[smartguyz]

Very interesting notion. I note that it IS several inches longer. How is the water cooling accomplished? Is there a radiator and water pump? How about a thermostat?

-Rob /forums/images/graemlins/grin.gif

 

[MossRoad]

3" is alot longer in that little engine compartment. Then you need to find a place for the radiator. On my PT425, there are pumps on both ends of the engines, so the crankshaft is capable of having mounts on both ends. The newer models have the pumps only on one end of the engine. The only other concern I would have is what is the diameter and length of the shaft coming out of the engine? Is it long enough to except the lovejoy(?) connection and will it except a pump mount?

 

[FOURTEEN]

/forums/images/graemlins/shocked.gif OK, maybe you could, but WHY???? /forums/images/graemlins/shocked.gif

/forums/images/graemlins/confused.gif After all that work and expense, where is the advantage???? /forums/images/graemlins/confused.gif

A Kohler 745 is the same L & W, but taller, and has 28 HP!! However, HP is not the limiting factor. My PT-425 never stalls out, bogs down, or shows any other signs of overloading the engine. At some point the hydraulics just won't do any more!

/forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[tracdoc]

I was wondering the same thing about liquid vs air cooled powerplants. During my visit to Tazewell earlier this week, I had a wonderful service session with Terry. Quite simply, Power Trac's philosophy is that liquid cooled powerplants add layers of complexity to the unit--water pumps, radiators, hoses, belts, thermostats, etc., which they feel are better avoided in the normal working environment for these machines.

 

[Abitnutz]

There are several good reasons I think to use the LC variant of this engine. There is a 28hp version of the air cooled engine but they had to use electronic fuel injection to gain that 3hp. Talk about increased complexity…wow. Anyway, I think a good case can be made that an LC engine is more desirable under most circumstances. They have lower oil temperature, lower oil consumption and have far more consistent overall engine temperature which results in longer engine life. This engine also develops more torque at 600 lower RPM and at a half point lower compression. It gets better fuel mileage and is quieter. It’s true I would have to consider the increased maintenance of a cooling system but to me it would be worth it. There is almost no difference in cost between these two engines. If they were to offer me a choice between two PT-425’s, one with a 25hp liquid cooled engine and the other with a 25hp air cooled engine. I would have to choose the LC model and pay an extra $200.00. Would I rather have a diesel? You bet! That would be almost irresistible! But the maintenance on those is higher and the cost of the engine would be much greater. Power-Trac would also have a much greater job of re-engineering to do. I guess I saw the LC variation of this engine that already lives in the PT-425 and thought what if? And wondered how little it would take to do it. I’m posting a picture if the 2 engines. I can’t address the issues about specific shaft length and diameters but as you can see from the pictures, these two engines are just about identical except for the radiator....Just a thought.

 

[Abitnutz]

2nd picture

 

[toolz_not_toyz]

I second that motion, of course. I would go with liquid cooled over air cooled for the exact reasons that Abitnutz mentioned. An LC doesn't add much more complexity to the setup: radiator, pump, hoses, fan. Big deal. This is really PT saying "We don't feel like doing it" for some reason or another.

Would PT have to reconfigure the engine compartment? Yes. But how many times have they done that now over the past three years?? Should be a breeze. Of course, by the way things have been headed with their evolving engine compartment design they'd probably mount the radiator at the front, behind the seat, where it wouldn't get any airflow and they'd relocate the gas tank under the seat so the operator could either blow up directly or indirectly if the fuel hose gets snapped off at the pivot point. /forums/images/graemlins/mad.gif

I already have an air-cooled Kohler in my JD lawn tractor. And I don't think it's a particularly great application. The PT needs something better when it carries a base price of $9500.

I've been quiet lately since I've been working on my other projects. But I sure hope PT makes some serious advances in their design between now and the time that I consider a PT 425. They need to address:

1) Gas tank location (it sure as heck shouldn't be attached to the engine compartement lid, nor should it live next to the exhaust).

2) Weak pivot pins (unless people have been overloading their PTs, this is a pretty good design flaw).

3) More powerful engine or at least some engine choices.

4) The ability to add removable weights as low to the ground as possible.

And all that other stuff that fourteen wrote about in his recent pros and cons thread. /forums/images/graemlins/wink.gif

 

[MossRoad]

They have several engine choices and sizes of machines.

As far as I can tell, none of their diesels are liquid cooled, they are oil cooled.

My engine has plenty of power for the size of the unit.

If they add weights to it, we will just abuse it more. Add weight, lift more, add more weights, lift even more, again and again until it snaps. /forums/images/graemlins/laugh.gif

The pivot pin problem hasn't bit me yet and I'm not sure it will until I start using a mini-hoe. I like my plastic gas tank on my older model. However, I like the layout of the engine compartment on the new models better. They keep evolving. I like that. /forums/images/graemlins/wink.gif

We also need to size a machine to the job. A small machine, while seemingly very powerful, will wear out and/or break when subjected to heavy loads over a period of time faster than a larger machine. That's why Power Trac offers so many different sized machines. We all want the most bang for our buck, but we have to be realistic as to what a machine of any size can do without subjecting it to a daily beating.

Again, I will stress that everyone should research these machines vary carefully before they buy them. They are not for everyone and if you do not enjoy mechanical work, when they break(and all machines break eventually), you will not be happy. It is a known factor. The warranty is a known factor, too. So is the absence of local dealer support. You have to be willing to accept this product on Power Trac's terms. That's the way they do business. We know this going into the deal. /forums/images/graemlins/crazy.gif

 

[smartguyz]

Wow, this thread is getting just a wee bit heated. However, I will wade in...

</font><font color="blue" class="small">( I second that motion, of course. I would go with liquid cooled over air cooled for the exact reasons that Abitnutz mentioned. An LC doesn't add much more complexity to the setup: radiator, pump, hoses, fan. Big deal. This is really PT saying "We don't feel like doing it" for some reason or another. )</font>

I used to think I wanted a liquid-cooled engine. It does allow the engine to have tighter tolerances because of the better control of temperature variation, etc. However, I have several liquid-cooled engines (in my cars/trucks), and I realize I don't really like it that much from a maintenance point-of-view - hoses to break and replace, coolant to recycle and replace, thermostats to go haywire, water pump leaking (!) and overall, more maintenance. On the other hand, assuming we keep the cooling fins cool, run the machine with reasonable limits (e.g. if it gets really hot outside, you might need to stop work and cool-down every so often - probably goes for both the tractor and ME /forums/images/graemlins/smile.gif) I appreciate the simplicity of the air-cooled designed. No, I'm not trying to be obstinant or insist my machine is more-wonderful - I just like the simplicity of having less stuff to maintain and break. I realize that my 20-year Snapper riding mower has an air-cooled engine, and still runs like a top. Never leaked, because there was nothing to leak!

</font><font color="blue" class="small">( I already have an air-cooled Kohler in my JD lawn tractor. And I don't think it's a particularly great application. The PT needs something better when it carries a base price of $9500. )</font>

I don't see that more complexity is really that much better unless something significant of value comes along for the ride. I'm not sure what tangible benefits a liquid-cooled engine would buy me in the 425-class machine. I would be happy to hear other opinions. I'm not being dogmatic here.


)</font>
2) Weak pivot pins (unless people have been overloading their PTs, this is a pretty good design flaw).

)</font>

I haven't had any problems here. Didn't know they were 'weak'. What exactly is the problem?

-Rob /forums/images/graemlins/grin.gif

 

[MossRoad]

Woops! Sorry if I sounded heated. Didn't mean to come across that way if I did. /forums/images/graemlins/blush.gif

Just want folks to be sure to think this stuff through before purchase. /forums/images/graemlins/wink.gif

 

[Abitnutz]

I guess I just don’t understand. If there is a better engine out there and it will go in with minimal engineering and essentially no cost increase, why wouldn't you offer it to your customers? Like I said, given the choice between two essentially identical PT’s, one with an air cooled engine and the other with a liquid cooled engine at about the same price…I bet the LC out sells its air cooled counterpart by a wide margin. Would offering an LC engine ultimately sell more Power Tracs? Probably not immediately but improving the product will always eventually increase sales through customer satisfaction. I have read the replies that the PT-425 doesn’t need anymore power, that they don’t bog down now. The LC engine variant is the same power.

<font color="blue"> </font>

Let’s face it; I want to run my tractor till I want to stop, not when it needs to cool down. I doubt that I would even recognize when the air cooled engine was over heating. None of mine ever had an oil temp gauge. Not doubt to keep from frightening me. The added maintenance of an LC engine I think is a myth. If it extends the life of the engine life then the maintenance is reduced. I’d rather replace a hose or thermostat than the bearings. There is a reason why you can’t buy air cooled cars and truck or pretty much anything but lawn mowers. Even Porsche liquid cooled its boxer engines.

Don’t over look the reduced noise as well. That may not be important to some but I find it worth considering.

 

[Abitnutz]

I hope that didn't appear ill tempered. I used to be a motorcycle mechanic years back. When they all swiched from air to liquid cooling...life imediately became better. I did come home with a pervasive odor of ant-freeze...I guess that's better than 90w gear il..yuck.

 

[Bob999]

<font color="red"> If there is a better engine out there and it will go in with minimal engineering and essentially no cost increase, why wouldn't you offer it to your customers? </font>

I have some question about your premise of "essentially no cost increase". I believe that you said that the engine costs more to buy. I doubt that the engine cost includes the radiator, hoses, coolant recovery tank, coolant, etc. that would add further cost. The data you posted indicated the engine is larger (longer). That would make the tractor itself longer, with more steel, more weight, etc. Finally, my experience is that maintaining a liquid cooling system does take time and money.

Thinking about it another way, PT makes a 30HP liquid cooled tractor (oil cooled). It is the PT 1430. Of course it is longer, heavier, and a lot more expensive.

 

[Abitnutz]

In an earlier post I pointed out that there is less than $200 in the price between the two engines. That does include the radiator, hoses and coolant tank. It does not include coolant but it doesn’t include oil either. I doubt that less than half gallon of anti-freeze will break anyone. When one is considering dropping upwards $10,000 on a tractor, a $200 increase in price is essentially no increase at all. Again, I think most people would pay that
The increased length of the engine is because of the radiator itself. It is less than 4 inches and radiators can be relocated to a more convenient place if need be. That may be where the bit of engineering comes in.
The point of this is not increased power but perhaps use a better, longer lasting, quieter and more desirable engine for about the same dollar amount. I really can’t believe that adding a very small radiator to a PT-425 will cause the builder to go to a PT-430 sized tractor. That’s essentially what we’re talking about here, just adding a radiator to a PT-425. The engine two engines are almost identical. One is the water cooled variant of the other

 

[J_J]

In reference to water cool engines, PT's mid 90's model, had water cooled engines. My 1445 has a 45 hp Industrial Ford engine. As far as I know, it has not had any problems. Just the regular oil change, air filter. PCV valve. It will probably run all day until it runs out of gas, and maintain the regular operating temp. My hydraulic fluid get quit warm.

 

[FOURTEEN]

Liquid cooled or diesel!! So many folks seem to want liquid cooled, or diesel, because they are supposed to last longer!!! How many PT-425 buyers will ever wear out their air cooled gas engines if they properly maintain them??!!

Ever since they became available, I have used synthetic lubs, currently Amsoil, in my air cooled gas engines! The synthetics ignore high engine temps! I have never had any engine service, other than tune ups, on any of them! (Currently: ’76 Power King tractor, ’84 Honda ATC 70, ’85 Honda lawn tractor, ’85 Honda ATC 200X, ’86 Yamaha Moto-4 80, ’90 chainsaw, ’91 Honda 250X, ’95 rotary mower, ’99 generator, ’03 chipper, and my ’04 PT-425.) I have never seen so much as a whiff of blue smoke from any of them! Over the years I have had several rotary lawnmowers that went to the dump because the wheels fell off, or the decks rotted out, not because the engines went bad! Actually, it would be OK if one of them did die, so I would have an excuse to buy something new!!! But it looks like they may well outlive me!!!
So, if these engines will last my lifetime, what the Hell do I need a LC, or diesel, engine for that may last two or three of my lifetimes!!??!!

Most of the noise from air cooled engines is due to the low quality mufflers provided, not just because they are air cooled!! The PT-425 is loud, but I doubt that just changing it to a LC engine would make it noticeably quieter.

AC, or LC, you still have to get rid of the same amount of heat! I vote for a more efficient hydraulic oil cooler before trying to find space for a radiator! It’s the hydraulics that are running way too hot on the PT-425, not the engine!! One of my next projects is to find a way to lower the hydraulic oil operating temperature on the PT-425.

/forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[SnowRidge]

Water cooled engines last longer than air cooled, and they make it easier for their designer to meet tougher emission standards. These are the reasons that there are virtually no air cooled automobiles being built anymore, and why so many motorcycles are now liquid cooled.

That said, the new liquid cooled Kohler is their first generation liquid cooled product, as far as I know. I don't think I would want to take a chance on it until the inevitable bugs are shaken out.

It would also make an already crowded engine compartment even worse, as far as accessibility goes.

The concept of water cooling in a PT-425 sounds good, indeed. The reality may not be so delightful. /forums/images/graemlins/frown.gif

 

[Schultz]

To stir the pot a little more, I would love having one of these Briggs & Straton Engines in a PT

L x W x H
17.09 x 17.05 x 21.58
Briggs LC Diesel

Vanguard Diesel LC

 

[BAGTIC]

The three inch difference in length includes an automotive type radiator. Kohler say the Aegis water cooled engines fit the same footprint as the air-cooled Commanders. I e-mailed PT several days ago before seeing this thread and asked if an Aegis could be substituted but did not get an answer, yet.

Why? More power. More torque. Besides the general rule of thumb is that liquid cooled engines are quieter, longer lived, more fuel efficient, more capable of handling brief overloads.

Also for those who like a cabin to keep warm a water cooled engine offers the possibility of a cabin heat exchanger for warmth. A liquid cooled engine would also be adaptable to an engine heater to pre-warm the engine on those extra cold days in order to ease starting.

I hope someone at PT is reading this. The Aegis engine would end any doubt on my part, get me off the fence, and ensure that a check would soon be in the mail.