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  1. #1
    Silver Member
    Join Date
    Aug 2005
    Posts
    112
    Location
    Chesapeake, VA
    Tractor
    PT 425

    Default Possible Overheating?

    After about 3 hours of moving mulch, my PT425 slowly shut off, like something electronic told it to. I had been driving it at less than half throttle thinking that since I had almost no weight in the bucket, no need to use full throtle. Also idled often as I raked in the mulch. What is the proper way of driving this machine so that it does not overheat? It would start right up and if I played with the throttle, it would be ok. If I had it at full throtle, I had to drive it fast to keep it from shutting off. Less than 1/3 throttle, seemed happier but lugged....

  2. #2
    Elite Member BobRip's Avatar
    Join Date
    Sep 2004
    Posts
    4,260
    Location
    Powhatan Va.
    Tractor
    2000 Power Trac 422

    Default Re: Possible Overheating?

    Might be trash in the fuel tank outlet, fuel line or the fuel filter. I have had this happen twice. Does it run better if you choke it a little while running at high speed. This is a sure indication of fuel starvation. You can disconnect the fuel line from the fuel pump and blow air into the line back into the tank. Don't use your mouth. You could drain the tank and then disconnect the fuel line at the tank. The trash is most likely at the tank outlet. It is smaller than the hose. Call me if you have any questions. Or PM.

    If when you let it sit for a few minutes it starts and runs for a while this is another indication of trash in the fuel system.
    Bob Rip
    Tell me and I will hear.
    Show me and I will see.
    Let me do and I will learn.
    Let me fail and I will understand.

  3. #3
    Veteran Member FOURTEEN's Avatar
    Join Date
    Jan 2004
    Posts
    1,028
    Location
    Efland - Triangle of North Carolina.
    Tractor
    2004 Power Trac PT-425

    Default Re: Possible Overheating?

    Quote Originally Posted by funpilot
    What is the proper way of driving this machine so that it does not overheat?


    These engines need to run at full throttle for proper engine cooling regardless of load! When you are off the seat, shut the engine off!
    "Expert on nothing with logical opinions about everything!!"

  4. #4
    Silver Member
    Join Date
    Mar 2004
    Posts
    245
    Location
    Colorado
    Tractor
    PT425

    Default Re: Possible Overheating?

    It's possible that your problem is the ignition switch. I have the same issue, and have not yet checked it out, but I was advised by PT that the ignition switch may need to be replaced.

    Turning the ignition switch "off" should ground the ignition system. If it does NOT, then the fuel solenoid shuts off, and it takes a second or two at half throttle to shut off, and maybe 5 or 6 seconds to stop if at 1/3 or less throttle.

    Because the engine stops by running out of fuel, it takes some cranking to get it started, and it stumbles and hesitates until the fuel line and carburetor bowl are filled again.

    The reason I have not replaced the switch (about $22 from PT) is that some time ago they instituted a $50 minimum order, and I have enough hydraulic filters to last me for the rest of my life since I added them to my previous small orders to make the $50!!

    When I return home in about three weeks, I'll be looking into whether the switch is actually bad or the grounding wire is broken or disconnected at either end.

    Hope this helps.

    Makr H.

  5. #5
    Veteran Member Barryh's Avatar
    Join Date
    Jul 2005
    Posts
    1,153
    Location
    Shannondale Mountains Harpers Ferry WV
    Tractor
    Former owner of a Power Trac -180 / Kubota BX-1500 with front end loader... Both were tough little machines Now a Craftsman Yard Tractor / John Deere 140 H-1 Garden tractor / Cub Cadet 108

    Default Re: Possible Overheating?

    Quote Originally Posted by funpilot
    After about 3 hours of moving mulch, my PT425 slowly shut off, like something electronic told it to. I had been driving it at less than half throttle thinking that since I had almost no weight in the bucket, no need to use full throtle. Also idled often as I raked in the mulch. What is the proper way of driving this machine so that it does not overheat? It would start right up and if I played with the throttle, it would be ok. If I had it at full throtle, I had to drive it fast to keep it from shutting off. Less than 1/3 throttle, seemed happier but lugged....
    I would have to agree with Fourteen, always run at full throttle. >>> Also idled often as I raked in the mulch. <<< I guess that's what you are saying ..... you got out and raked in the mulch.

    If you get off of the machine I would turn it off. It could be dangerous to leave the Pt running while you are out of the saddle. You can hit the treadle by mistake when getting back in and run over your leg or someone else. If you do have to leave it running, I would just make sure your brake is on.

    I run mine at idle just at startup with a little choke. Just until it starts to idle smooth, then I go full throttle the rest of the time until I turn it off. When I do turn if off, I back the throttle down about half way to eliminate the famous backfire.

    I would also agree with Bob, if you haven’t done it yet, check out your fuel system for debris. I found a lot of it in my PT from the factory. I took off the tank, changed out the fuel lines, and flushed the rest of the system. I also changed the gas filter. It made a big difference.

    As for the ignition, I am waiting for it to go bad. When the time comes, I will look into a better ignition switch, other than the one PT offers. I think the one from PT looks kind of cheap.
    Last edited by Barryh; 04-25-2007 at 10:17 AM.
    Barry / 1968 John Deere 140 H-1
    __________________________________________________ _____

  6. #6
    Platinum Member Phils's Avatar
    Join Date
    Sep 2004
    Posts
    767
    Location
    Cherokee, CA
    Tractor
    PT-422

    Default Re: Possible Overheating?

    I'd vote that your shut-off may be fuel related, not electronic. When it happens again, take the cap off of the gas tank and look in. If you see bubbles coming up from the tank outlet, you have a vaporlock problem. Shuttinig down after a few hours is EXACTLY what I was dealing with until 1) I removed the debris at the fuel tank outlet and 2) replaced the clear fuel line with better and 3) installed an electric fuel pump and 4) rerouted the fuel line to the right (cooler) side of the engine, which can't be done using the stock mechanical fuel pump mounted on the left side.

    Mine doesn't shut down now but I know that gas is still vaporizing in the lines before the carb, just not enough NOW to shut it off. It IS enough to cause the engine to run hotter because of the lean fuel condition. I can tell also because I can hear the difference (when restarting after a short break) in the electric pump, whether it's pumping liquid or vapor.

    I'm giving serious consideration to installing an electric radiator cooling fan on the right side of the engine cover that'll blow across the exhaust end of the motor and out the muffler side. I haven't decided whether to wire it to be "always on" or have it come on when the hydraulic fan does.

    Phil

  7. #7
    Veteran Member
    Join Date
    Jun 2006
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    2,130
    Location
    West Cascades Washington State
    Tractor
    PT 422

    Default Re: Possible Overheating?

    The switch i bought was an Oregon 33-399. Replacement for Scag #48798 and Briggs #493625. I think it was $15 at the tractor store.

    422 w/robin engine.

  8. #8
    Veteran Member Barryh's Avatar
    Join Date
    Jul 2005
    Posts
    1,153
    Location
    Shannondale Mountains Harpers Ferry WV
    Tractor
    Former owner of a Power Trac -180 / Kubota BX-1500 with front end loader... Both were tough little machines Now a Craftsman Yard Tractor / John Deere 140 H-1 Garden tractor / Cub Cadet 108

    Default Re: Possible Overheating?

    Quote Originally Posted by cqaigy2
    The switch i bought was an Oregon 33-399. Replacement for Scag #48798 and Briggs #493625. I think it was $15 at the tractor store.

    422 w/robin engine.
    Thanks for that info, I will look into it for my PT. How do you like it ? better defined key? better quailty I'm sure.
    Barry / 1968 John Deere 140 H-1
    __________________________________________________ _____

  9. #9
    Veteran Member
    Join Date
    Jun 2006
    Posts
    2,130
    Location
    West Cascades Washington State
    Tractor
    PT 422

    Default Re: Possible Overheating?

    Quote Originally Posted by Barryh
    Thanks for that info, I will look into it for my PT. How do you like it ? better defined key? better quailty I'm sure.
    I think it's a direct replacement. Probably just as cheap but it's cheaper.

  10. #10
    Silver Member
    Join Date
    Aug 2005
    Posts
    112
    Location
    Chesapeake, VA
    Tractor
    PT 425

    Default Re: Possible Overheating?

    OK, I definitely have bubbles coming out of the fuel drain from the fuel tank. I see NO debris in the outlet. I never had this problem until I took it in for maintenance. What could they have done to aggrevate the situation to cause it? I presume to do any of the work you suggested, I will have to siphon the gas out of the tank .... I am sure for more talented men like you this is a non issue. I'll bet it has been my one and only problem since I got it back from maintenance. Otherwise, best machine I have ever owned. But, I keep looking at the diesel model .... hmmm
    Last edited by funpilot; 04-29-2007 at 01:53 PM.

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