New to the forum

[twood78]

I was bitten by the Power Trac bug back in 1998 when I bought my 422. Hardest-working little machine ever built. Bought a custom trailer rig in July 2016 to house all the toys. I needed an upgrade, so I sold the 422 and bought my 425 in February 2017. I like the 425 better because of the extra power and reach, and the treadle is a huge improvement.

The Subaru/Robin engine has, unfortunately, not improved. Actually gotten worse. The fuel shut-off solenoid in the carburetor failed to work on my first job and flooded the engine on the jobsite twice. Also vapor locks every time it is worked hard in warm weather. Solved the fuel shutoff problem by adding a solenoid valve in the fuel line (redundant). Attempted to solve the vapor locking by replacing the mechanical fuel pump with an electric one under the tank, but the problem persists. Taking her back to Tazewell to see Terry next week for some head-scratching and heat shielding.

I really love these little machines and the folks in Tazewell, but this problem's gotta be fixed...

 

[Wagtail]

G'day Mate and welcome to TBN from Downunder.

Enjoy the site.

 

[marrt]

Welcome.

Consider adding a fan to the right side of the tub blowing across the exhaust. The hot weather fueling problem is a "known issue" with the Subaru and I'd be shocked if PT has a solution...other than swapping in a Kohler.

I had the same problems as you with the POS Robin 25HP. Only, in my case, the needle valve (I think mine didn't have a shut off solenoid) flooded the engine when I left the tractor setting for a few days. Now, one is "supposed" to check the oil before each start up. This is one of the reasons why. If I'd done so, I would have noticed the high oil level due to the extra fuel getting past the piston rings and would not have killed my engine when attempting to start the thing. Even so, good riddance. I hated that engine. Replaced it with a Subaru 35HP engine that's made by Generac. But that's a whole different story.

Anyway, the fan should help (but may not completely fix) the fueling problem.

 

[MossRoad]

Don't know if it would help you or not, but on my Kohler, when the mechanical fuel pump died from a torn diaphragm, and I found a new one was ridiculously high priced from everywhere, I replaced it with a vacuum fuel pump quite inexpensively. There's a thread on it here somewhere. I tapped the vacuum off of the valve cover, where I gutted the mechanical one from.

Oh, and welcome to TBN! :thumbsup:

 

[MossRoad]

Don't know if it would help you or not, but on my Kohler, when the mechanical fuel pump died from a torn diaphragm, and I found a new one was ridiculously high priced from everywhere, I replaced it with a vacuum fuel pump quite inexpensively. There's a thread on it here somewhere. I tapped the vacuum off of the valve cover, where I gutted the mechanical one from.

Oh, and welcome to TBN! :thumbsup:

 

[MossRoad]

Here's my mechanical to vacuum fuel pump conversion. There's more talk in that thread about a lot of different issues, so I linked to the post directly.

https://www.tractorbynet.com/forums...attery-broken-exhaust-stud-2.html#post4872729

 

[twood78]

Thanks for the welcome! I've done about everything imaginable with the PT400 series except climb trees and prevent vapor lock. My current set-up is a 425 on a trailer rig housing it (love the quick-attach plate mounting) along with 10 cu ft bucket, box blade, 48" mower, forks, auger head with 6" and 12" augers, trencher, concrete mixer, winch, and hitch plate. Visiting Tazewell next week to add a trench filler, larger concrete mixer, and some heat shielding for the vapor locking.

Terry acts surprised that I am experiencing vapor lock, but has offered that they can install some heat shielding that will help. The PT425 has serious heat management issues. After normal operation and parking of the tractor, the fuel shutoff valve in the carburetor will close, but the heat soak will cause the carburetor float bowl to boil dry. This makes it difficult to start at the next use (rough on starter and battery). Installation of a primer bulb or electric fuel pump solves this problem nicely. All the heat, however, soon had my primer bulb cracking, so I replaced it with an electric fuel pump. Vapor locking is still happening, however, and the primer bulb made recovery much easier and faster than the electric fuel pump. If heat shielding doesn't work, a high-pressure/high-flow fuel pump with 4 psi spring-check valve on a return line to fuel tank will keep the fuel cool and liquefied, or a secondary cooling fan might be in order. How much electrical load can these engines sustain?

 

[Thomas]

:welcome: to TBN...enjoy.

 

[MossRoad]

I do not know about the electrical load. My 2001 Kohler has only a 15 amp alternator. Don't know about the other engines.

 

[agjones]

I believe that subaru has 12-15 amps available.

EH72-2(25.HP) - Industrial Products Co., Ltd.

 

[cqaigy2]

I remembering fighting the heat problem on my robins 22hp. Tried adding heat shielding to the part of the exhaust pipe that was onside the engine compartment. Added high temp insulation wrap to the exhaust pipe. Replaced fuel line with heavy duty one. Added fuel-line insulation and covered all of it.

The one thing that helped the most, was removing the crud that was in the elbow, at the bottom of the fuel tank. I'm guessing it was some kind of white sealant, they use and some must have spilled or dripped inside the tank and made it's way down into the elbow. It was white, and with my less than stellar eyesight, i missed it the first time looking.

About the fuel shut off solenoid issue, I put in a fuel shut off after filling my crankcase full of gas.

The best fix for the fuel issue i was having, was to replace the robins with a kohler. I held off on that fix until i had broken the robins, however.

 

[marrt]

Also...with this much heat, I'd also be worried about the condition of the oil in the engine. Once a certain temperature threshold is reached, oil deteriorates very rapidly. At the very least, I'd definitely consider running synthetic oil. It's cheap at Walmart and good insurance.

 

[m5040]

I only have a PT180, but I would imagine that the heat issue is common with them all. One thing I would suggest that works for me is, if you are working the tractor hard and it is hot, to open the hood and idle the engine about 3 to 5 mins before you shut it off. You may think this is a long time but that is what turbo charged engines are required to do mostly to cool the turbo, but I think it is good practice with these engines too. If I don't the engine wants to keep running with the ignition off, not good.

 

[MossRoad]

I have no heat issues with my 2001 model PT425 and Kohler engine with Kohler exhaust. None. My layout is the tram pump is in front of the engine and my PTO and AUXPTO pumps are behind the engine. The factory exhaust is on the rear of the engine and exits out the rear of the machine, behind the rear expanded steel. While this setup has it's expenses and quirks, like it needs the auxiliary PTO stub shaft on the front of the engine to run the tram pump, and the muffler has to be removed to change the battery, I think it's the best setup I've seen. I originally liked the setup where the engine was in the rear and all 3 pumps were out front along with the battery, I don't like the Power Trac manufactured exhaust systems. I think they should go back to a Kohler engine and Kohler factory exhaust/muffler.