How many hours can you expect on a gas engine Power Trac?

[m5040]

With proper maintenance and no abuse, how many hours have people experienced with the gas engine models of PT? What is the weakest link and what to watch out for when looking at used tractors?

 

[CADplans]

The number of hours is totally dependent on what the duty is,,
A woodsplitter encounters almost no dust,, the oil stays clean,, L O N G engine life.

I ran a 14HP Kohler powered garden tractor mowing for a few years,,,
It was obvious that the oil was capturing large amounts of dirt that the mower was throwing into the air during a drought.
The engine oil would stay clean when there was some moisture in the soil,,,

So,, what will the engine be doing??

 

[4570Man]

I’d say if it makes 2,000 hours on the motor you’ve done pretty good. I’ve seen a lot of the Kohlers that didn’t make it that far.

 

[RickB]

I’d say if it makes 2,000 hours on the motor you’ve done pretty good. I’ve seen a lot of the Kohlers that didn’t make it that far.

I’d have to agree. I’ve seen lots of Kohler and Kawasaki twins on zeroturns that were heading for being used up at or before 2000 hours.
As many or more than what were strong and sound at 2400 hours.

 

[m5040]

I am just looking for an average life expectancy. Most tractors I would guess get a pretty spread out work load from mowing to loader work with the worse thing being trencher work. I see a lot of commercially used tractors for sale with around 2000-2400 hours and was thinking maybe there is a reason for that.

 

[MossRoad]

I've got about 700 on the PT425 Kohler Command Pro 2001 model year.

Hopefully Bob will chime in. I think he's got the highest hour PT on this forum.

There's a lot of variables. Dirt, dust, load on the engine, preventative maintenance, etc...

Here's what's failed on mine in the past 18 years that's even remotely engine related:

- I'm on my 2nd Kohler starter. Starting a gas powered PT is very hard on the starter, especially in cold weather, as it's pushing all three pumps in addition to the compression. Kinda engine related, but not the engine itself
- Mechanical fuel pump failed about 1-2 years ago. It's built into the valve cover and $$. So I gutted it and installed a cheap vacuum pump fed off the old mechanical housing. There's a thread on it here somewhere. Cheap and easy repair.
- Valve cover bolt broke when removing cover to get to fuel pump issues. Not a fault with the engine.
- Exhaust stud broke when I was removing manifold to change battery. Stupid design, no longer an issue with current designs, and hardly an engine failure issue.
- Choke cable seized up due to heat from exhaust about 2 years ago. Again, not a fault with the engine. Changed the throttle cable while I was in there.

I believe I'm still on my original spark plugs. I may have changed them one time.
No carb adjustments.
No valve adjustments.
2nd air cleaner.
14 engine oil filters @ 50 hours per filter.

That's about all I can think of.

 

[MossRoad]

I am just looking for an average life expectancy. Most tractors I would guess get a pretty spread out work load from mowing to loader work with the worse thing being trencher work. I see a lot of commercially used tractors for sale with around 2000-2400 hours and was thinking maybe there is a reason for that.

Back around 1990 I purchased a very used International 2500b. It had a 4 cylinder gas engine. 50hp PTO, hydro tranny, tractor loader with PTO. Full cab. It was very abused and had well over 4000 hours when I bought it and the hour meter wasn't working. I put at least another 500 hours on it over the next 10 years. It was still running strong when I sold it.

Industrial gas engines are not like air cooled small engines, so it's not a good comparison.

Remember, these gas powered Power Tracs are nothing more than a lawn tractor type engine driving hydraulic pumps at near constant 3600 RPMs. They don't get revved up and down. It's actually detrimental to run them at lower RPMs because it doesn't power the cooling fan and doesn't lubricate the engine as well. They are designed for 3600 RPMS constant. At an average of 50 hours per year, 20 years is not unreasonable for 1000 hours. They are inexpensive to replace all things considered.

 

[m5040]

Roger that. I will have a problem as I hate to rev engines to their governors. But you are right with the 20 years going by... Maybe someday a small diesel will be available for repower.

 

[MossRoad]

Roger that. I will have a problem as I hate to rev engines to their governors. But you are right with the 20 years going by... Maybe someday a small diesel will be available for repower.

It's not needed on this size machine. The larger PT's, any model over a PT425, are diesel. Oil cooled Deutz engines.

 

[4570Man]

It's not needed on this size machine. The larger PT's, any model over a PT425, are diesel. Oil cooled Deutz engines.

Maybe not necessary but it would last longer and burn less fuel.

 

[MossRoad]

Maybe not necessary but it would last longer and burn less fuel.

Get some prices on name brand 25hp 3600 rpm diesel engines that will fit in the same footprint. Let's see how the prices compare. It would be interesting. My 2001 25hp Kohler burns just about 1 gallon per hour at full throttle. Diesel costs 12% more than gas right now. So we'd have to figure that in as well.

 

[m5040]

my 4 cyl Kubota generator 10kw burns 1/2 gal hour at moderate load.

 

[4570Man]

Get some prices on name brand 25hp 3600 rpm diesel engines that will fit in the same footprint. Let's see how the prices compare. It would be interesting. My 2001 25hp Kohler burns just about 1 gallon per hour at full throttle. Diesel costs 12% more than gas right now. So we'd have to figure that in as well.

There’s no need to run 3500 rpm if it was designed not to to start with. I never claimed the upfront cost was less. Not running at 3600 rpm would lead to longer pump and engine life.

 

[MossRoad]

There’s no need to run 3500 rpm if it was designed not to to start with. I never claimed the upfront cost was less. Not running at 3600 rpm would lead to longer pump and engine life.

The pumps have to turn at 3600 rpm to get the proper flow and pressure. They're direct mounted to the engine. If the engine can't turn 3600rpm, then you're going to have to add pulleys and belts, or gears to drive them, or use different, more expensive pumps that can get the flow and pressure at lower rpms, etc.... all adding cost.

 

[4570Man]

Not if it was designed to run slower to start with. I agree a diesel repower would be a nightmare.

 

[m5040]

To start with it would be good to get one of those cheap tachometes to see what the actual engine rpms are when you are working under a heavy load. It may be down as low as 2600 rpm anyways. Some of the air cooled emissions diesels are higher rpm. but any repower is very difficult.

 

[MossRoad]

What I'm getting at is you'd have to do a lot of re-engineering to get a 25hp diesel engine, three pumps, fuel tank, battery, hydraulic cooler, air cleaner, exhaust system squeezed into the tub of a PT400 series chassis, and keep the cost the same as a gas powered PT425. I don't think you can, over the lifetime of the machine, break even on the added cost of the diesel engine and different pumps, even if you could get them to fit into the tub.

With the average small tractor owner putting only about 50 hours per year on a machine, a 2000 hour gas engine will last 40 years. Chances are you'll be dead before it wears out. More likely the hoses or pumps or wheel motors will fail way before the engine does.

 

[MossRoad]

To start with it would be good to get one of those cheap tachometes to see what the actual engine rpms are when you are working under a heavy load. It may be down as low as 2600 rpm anyways. Some of the air cooled emissions diesels are higher rpm. but any repower is very difficult.

Any time I hear the engine RPMS change while working, I just let off the foot pedal enough to get the sound back to normal. It's intuitive after just a couple hours of operation. Doesn't matter if its mowing, brush cutting, loader work, climbing steep hills, etc.... you just operate these things by your senses. Kinda like flying stick and rudder seat of the pants. Full throttle all the time. Listen for changes. Your feet adjust the directional speed automatically. It's a thing of beauty.

 

[ernemats]

On my 422 I changed the engine out at 2,924 hours on it. Could have had it repaired but I had another 22 hp engine I bought years ago as a spare so I just put it in. I don't run it at full rpm's I just run engine speed at what is needed, using mini hoe fast idle , mowing probably 3/4 throttle and just running around or using loader just what I feel is needed. My ground is very hilly going up hill half to full throttle depending on slope going down hill slow idle speed. I will admit I do not change oil and filters at 50 hours more like 100 hours, I believe changing oil depends a lot on what conditions tractor is used for.

 

[marrt]

I used to frequent another website focused on commercial mowing and those guys were getting up to 4000 hours on a Kohler 25 HP horizontal engine. At the time, the horizontal engine (like the one in the PT) was MUCH more durable than a vertical Kohler engine. I have one in my Exmark and the oil stays remarkable clean due to the heavy duty air filter. If I were to guess, I'd say a heavy duty air filter (Donaldson type) will make the most difference in longevity, other things being equal. You'd be surprised to know how much dust gets past any air filter (read an interesting article on this subject once).

I'm also a fan of using synthetic or synthetic blend oil in air cooler engines due to its ability to maintain stability and viscosity at much higher temps than conventional oil. Also, I'd recommend Shell Rotella Diesel oil due to it's high levels of Zinc (1200 ppm). The amount of Zinc, an important anti-wear additive than protects the engine on cold startups, has been significantly reduced in most "gasoline motor oil" for emission reasons.