PT 425 Kohler 25 HP Engine

[Spanky100]

Questions on the 25 HP Kohler Gasoline Engine used on the PT 425.

- is that an air cooled V twin horizontal crankshaft (730 cc) with single carb? (my guess from picture and limited description on PT Website)

- Kohler model number?

- how many hours would you expect with that engine before reduced compression/power/high oil consumption/hard starting would drive you to a rebuild or replacement engine? (I know time can factor in so lets think 100 hours per year with maintenance as called out in manual)

- What is the expected fuel burn in Gallons Per Hour for moderate to heavy grass cutting with 60 inch finish mower and grades 5 to 10 degrees (8 to 18 percent slope)

- is the engine lubrication the limiting factor for PT 425 slope capability or does the tractor stability limit out first?

learning more about the different PT Models

Thanks

Wayne

 

[Lnk]

After spending the last 4-5 years reading this forum, I think 1500-2000 hours is a safe range. So at the 100/year rate you are looking at 15-20 years. My limited experience with the robin 25 HP engine seems like around 1 gallon per hour. So you are looking at using between $4200-$6000 dollars worth of fuel at an average price of $2.50-$3.00/ gallon. A new engine seems like $1500-2000. Some of us spend more on the non-ethanol gasoline, so the numbers would be higher. That said, most contractors charge $75+ per hour for site work machine time.

I personally think these engines if well taken care of can last even longer, perhaps with less power as it ages.

Hope that helps.

Lnk

 

[MossRoad]

I do not know the model of the current Kohler engine that PT is reportedly using.

I have a CH25 in my 2001 model year PT425. It has about 1000 hours on it, so about 50 per year.

Issues I have had with this engine are:

- the mechanical fuel pump died (hole in diaphragm). I replaced it with a sub $20 vacuum pump.
- the valve rocker nut on one side came loose at around 950 hours, which caused a push rod to pop out from under the rocker. I could see it through the oil filler cap. When going to remove the valve cover, one of the valve cover bolts snapped off in the head with very minor pressure from me. I was able to just replace the push rod in it's place and torque the nut back down (no valve adjustment needed as it's hydraulic lifters), however, the bolt is still broken in there, which makes for a poor gasket seal, causing a slight oil leak, which makes a fire hazard.

Then several hours later, the other side did the same thing with the rocker bolt, only that time the push rod came up and poked a hole in the valve cover. Again, when going to remove the valve cover, another valve cover bolt broke the same way. So now I have two leaky valve covers.

I am still working on getting the bolts out without destroying the heads. New heads come to about $500 + valve covers, as the old covers don't fit new heads.

- on the old PT425 design, it uses the stock Kohler muffler, and that has to be removed to get to the battery. Guess what? Removing the exhaust stud nut, a stud broke off. I was able to extract that. So I took the opportunity to replace all of the exhaust studs. Don't think the battery under the muffler is a problem on the newer models.

- I've replaced 1 starter that died, and one starter that I mistook as dead, but later found I had the PTO switch on so it wouldn't start so I have a spare starter.

Other than that, I've had no engine problems.

Mine has a 5 gallon plastic fuel tank that leaks around the cap if I put more than 4 gallons in it. I can run about 4 hours on that 4 gallons, so about 1 gallon per hour mowing with the 60" mower or 48" brush cutter at full throttle. I'd say about 1.1 gallons per hour.

From my Kohler engine manual, the engine is limited to 25 degrees of continuous operation due to the lubrication system.

It's a pretty stable little machine. I do not know what the actual tipping angle of it is on a side slope. I try and take mine up and down. I have a couple 20 degree side slopes and that's not comfortable. Glad I have the arm rests.

You'd want to call Terry at PowerTrac to get the current specifics from them. They are very friendly and helpful.

 

[Goose1776]

I just bought a new 425
I’ll try to take pics of engine model number tomorrow
But I do know the machine is slope limited due to engine, not the machine. I asked about that specifically when I was there.
I will say, that the machine is capable of slopes that are uncomfortable for me. Lol

 

[Goose1776]

Pics of current engine model number,
Looks to be 730 model number
and layout.
I haven’t mowed enough to know the gallons per hour, but have heard others say gallon per hour, and that seems reasonable to me
I do know, at 1/2- 3/4 throttle just using the grapple moving brush, using the forks to move stuff around, etc. it sips fuel.

 

[Spanky100]

After spending the last 4-5 years reading this forum, I think 1500-2000 hours is a safe range. So at the 100/year rate you are looking at 15-20 years. My limited experience with the robin 25 HP engine seems like around 1 gallon per hour. So you are looking at using between $4200-$6000 dollars worth of fuel at an average price of $2.50-$3.00/ gallon. A new engine seems like $1500-2000. Some of us spend more on the non-ethanol gasoline, so the numbers would be higher. That said, most contractors charge $75+ per hour for site work machine time.

I personally think these engines if well taken care of can last even longer, perhaps with less power as it ages.

Hope that helps.

Lnk

Lnk

Great information. It is a significant help. Thanks

 

[Spanky100]

I do not know the model of the current Kohler engine that PT is reportedly using.

I have a CH25 in my 2001 model year PT425. It has about 1000 hours on it, so about 50 per year.

Issues I have had with this engine are:

- the mechanical fuel pump died (hole in diaphragm). I replaced it with a sub $20 vacuum pump.
- the valve rocker nut on one side came loose at around 950 hours, which caused a push rod to pop out from under the rocker. I could see it through the oil filler cap. When going to remove the valve cover, one of the valve cover bolts snapped off in the head with very minor pressure from me. I was able to just replace the push rod in it's place and torque the nut back down (no valve adjustment needed as it's hydraulic lifters), however, the bolt is still broken in there, which makes for a poor gasket seal, causing a slight oil leak, which makes a fire hazard.

Then several hours later, the other side did the same thing with the rocker bolt, only that time the push rod came up and poked a hole in the valve cover. Again, when going to remove the valve cover, another valve cover bolt broke the same way. So now I have two leaky valve covers.

I am still working on getting the bolts out without destroying the heads. New heads come to about $500 + valve covers, as the old covers don't fit new heads.

- on the old PT425 design, it uses the stock Kohler muffler, and that has to be removed to get to the battery. Guess what? Removing the exhaust stud nut, a stud broke off. I was able to extract that. So I took the opportunity to replace all of the exhaust studs. Don't think the battery under the muffler is a problem on the newer models.

- I've replaced 1 starter that died, and one starter that I mistook as dead, but later found I had the PTO switch on so it wouldn't start so I have a spare starter.

Other than that, I've had no engine problems.

Mine has a 5 gallon plastic fuel tank that leaks around the cap if I put more than 4 gallons in it. I can run about 4 hours on that 4 gallons, so about 1 gallon per hour mowing with the 60" mower or 48" brush cutter at full throttle. I'd say about 1.1 gallons per hour.

From my Kohler engine manual, the engine is limited to 25 degrees of continuous operation due to the lubrication system.

It's a pretty stable little machine. I do not know what the actual tipping angle of it is on a side slope. I try and take mine up and down. I have a couple 20 degree side slopes and that's not comfortable. Glad I have the arm rests.

You'd want to call Terry at PowerTrac to get the current specifics from them. They are very friendly and helpful.

Moss Road

Great detail and information from a 20 year PT425 owner and operator. I hope to call Terry and get to PowerTrac this fall. Appreciate your information and know if I get a PowerTrac this group and PT are always willing to help.

Thanks

 

[Spanky100]

I just bought a new 425
I’ll try to take pics of engine model number tomorrow
But I do know the machine is slope limited due to engine, not the machine. I asked about that specifically when I was there.
I will say, that the machine is capable of slopes that are uncomfortable for me. Lol

Goose
Appreciate the information and nice to see a new purchaser make the PT 425 choice. I have been looking at a Ventrac 4500 for a few years to mow fields that have some slope sections that are beyond my comfort level on a traditional tractor with 3 point rotary cutter.

This PowerTrac site has caught my interest and expanded my search to PowerTrac equipment. I think the PT design Front End loader is an advantage over Ventrac 4500.

Thanks

 

[Spanky100]

View attachment 708317
View attachment 708319
Pics of current engine model number,
Looks to be 730 model number
and layout.
I haven’t mowed enough to know the gallons per hour, but have heard others say gallon per hour, and that seems reasonable to me
I do know, at 1/2- 3/4 throttle just using the grapple moving brush, using the forks to move stuff around, etc. it sips fuel.

Goose

Thanks for the great pictures. Nice to see the plastic fuel tank that Moss spoke of has ben replaced with what looks like and aluminum fabricated tank with a nice cap.

 

[TractorGuy]

I wonder why they don't just use a less expensive, more reliable, Briggs & Stratton engine.

Briggs & Stratton 44S977-0015-G1 25 HP Professional Series Engine

This genuine 724cc Briggs & Stratton twin cylinder engine offers dependable power for your equipment needs. With a power rating of 25 horsepower, this engine features a premium Dual Clean air filtration system, electric starter, and maintenance-free Magnetron electronic ignition. With a...

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