425 Need help

[cqaigy2]

And my lean running problem was taken care of when i cleaned all the crap out of the fuel delivery system. Connector at bottom of fuel tank full of plastic glue stuff and all the way into the carb and fuel shut off solenoid.


And thank you tractorbynet for spell check

 

[MuncyBob]

While I have not had any vapor lock problems I can say that the bubbling in the fuel tank was reduced considerably when I took the poor man's(and lazy!) approach and simply lined the fuel line with aluminum foil. One day I'll replace the line and filter...but until then this seems to be a fix.

 

[cqaigy2]

While I have not had any vapor lock problems I can say that the bubbling in the fuel tank was reduced considerably when I took the poor man's(and lazy!) approach and simply lined the fuel line with aluminum foil. One day I'll replace the line and filter...but until then this seems to be a fix.

I did that for a while too, actually still doing it.

 

[Central_PA_Chris]

OK, couple answers. Play date for the tractors went well (thanks ahartman!). It was good meeting a local PT owner & his family & pets it was a fun time on a nice sunny, but cool day.

His 425 had the Kohlar (mine's the Robins) 25HP engine. I think his was a '03. His handled hills better than the newer, went nice and steady up a hill that mine (with mower on the front but PTO off) bogged down on. It was an incomplete test, only ran mine for 40 min or less and it was a cool day, so not up to the higher temps where the issues are more noticeable.

The other member also concluded that something was funny and not right about my PT. Basically the PT gets to a point where it stops going uphill, while the treadle is partly depressed, but the engine doesn't sound like it's under much load, it doesn't bog down, just sits there not going anywhere, press a but further on the treadle, and sometimes it starts going uphill again, sometimes it stalls (no stalls today).

The hydro fluid has to be going somewhere, why would the fluid bypass the wheels and maybe/sometimes start them spinning when treadle depressed more?

I did come away with a list of PT to do's, tops is check the towing/bypass valve to make sure it's fully closed. I/we concluded that that's probably not it as it doesn't slide downhill on big hills, but I'll give it a try.

I can replicate the lack of torque when loading the PT onto my trailer, I have a tilt bed, so it's a 3-4" lip to get onto the bed. If the PT is not in motion when at that lip it will sit there and when treadle is depressed not do a darn thing, no tire spinning, no engine bog down. I have to get a running leap to bounce up onto the bed. I'm totally ignorant about how the system really works, but it's kinda like a hydraulic overload bypass is opening up way too soon rather than giving the wheels torque to spin in lowest/first/barely depressed treadle position.

RE prior questions:
I have noticed it popping out of float occasionally, I greased it up and seems to be working again. The joystick base was a bit rusted when it came back from the shop and that's when it started doing that little shenanigan.

Yes, I have found that picking the mower up and eliminating that drag on the front can help get it moving when it's having issues with a slope.

Thanks for all the tips on the fuel issues, they should fix me up on that front.

I don't have a lot of time (or room in the shop) at the moment, but I guess this winter I'll log into a bunch of PT cooling projects. Just gotta figure out the wheel torque issue and maybe, just maybe, the old 425 will be worth keeping.

 

[SnowRidge]

Did you get a manual with the machine? It should have a hydraulic plumbing diagram. It's not the best diagram in the world, but it is usable. I would definitely verify that every hydraulic hose runs to the right place, especially since you had a shop working on the machine that wasn't familiar with PTs.

If the machine isn't going anywhere with the treadle depressed, you need to check and see if the control on the variable volume drive pump is moving in concert with the treadle. That's easy to do on the older hydroback/cable models like mine, but I don't know about the hydraulically operated control that yours has. The control rotates one direction when the right treadle is depressed and the other direction when the left treadle is depressed. The amount of rotation should be roughly equal for each direction.

If the pump control is moving appropriately, then it might be a bad pump, which wouldn't be good news. The pumps have to have the air bled out of them anytime the hydraulic circuit is disconnected. If that isn't done, they are susceptible to damage. Is there any chance that the shop that worked on the machine, disconnected the hydraulic lines or removed the hydraulic filter and didn't properly bleed the system?

If it is the pump, and it was bad from the get go, it might still be under warranty. Aside from the engine, it is the most expensive component on the machine. Somebody posted that one or more of the pumps have a two year warranty. That would be worth checking into.

If it hasn't already been done, change the hydraulic filter and bleed the system before you run the machine anymore. It might be bad or partially clogged.

 

[J_J]

Central PA Chris,

Have you ever put a hydraulic pressure gage on the system? A $15.00 hydraulic gage will tell you what is happening with the system. You can put a tee and quick disconnect in each of the circuits and analyze the situation. A hydraulic shop will charge you about $65.00 to look at the system. I would call Terry at PT and ask for the pressure readings that should be present in the different circuits. It sounds like you have a weak pump. Can you verify that the fwd/reverse lever on the pump is operating at it's full range. There should be enough torque in low range to operate some hills. Is your PT still under warranty?

 

[Central_PA_Chris]

I have to run to Pittsburg for 2 days and gotta flee out the door right now, but here's a quickie. I don't think it's the treadle as when it is going up a hill in slow/least depressed mode it will stop going up hill with no change in treadle pressing and just sit there w/treadle in same position.

The hydraulic system as a whole works well, always seems to be enough PTO power to run the mower can cut everything quite well. Ahartman said he thinks it cuts brush better than his (though could be blade sharpness differences).

It has been doing this same thing since I picked it up. I had difficulty getting it on my trailer in the PT parking lot in Tazwell, I wrote it off to my inexperience in use at the time. Machine is now +-15 months from purchase, 30.9 hours on it.

It will go up some hills, but many fewer when everything is hot.

I don't think the shop did any disconnection of hydraulics.

I'll give Terry a call when I get back from this quick trip. I can easilly video the trailer loading issue and mail/email that down to him to look at since that at least is easily replicable.

 

[SnowRidge]

There are three hydraulic systems on the machine, not one. Other than the mechanical coupling of the pumps and the common hydraulic reservoir, they are completely independent. The fact that the PTO works fine has no bearing on the wheel drive system, except when the combined load of the two systems exceeds the motor's available power output, in which case it bogs down. That isn't happening, so you can disregard the PTO system in this case. You need to look at the drive system and its controls.

Two of us have suggested that you verify that the treadle is moving the drive pump control properly. We made these suggestions for a reason. If nothing else, eliminate the easy stuff first. You don't want to tear into the drive system if there is air in the treadle control lines, or it is something else of that ilk. Air in any hydraulically operated control system will result in that system operating improperly. Temperature changes may exacerbate it. You need to check and eliminate the treadle system as the root cause of the problem, especially since you state that the engine doesn't seem to be under any particularly heavy load. Then move on to the expensive part, the pump.

 

[ldabe]

Snowridge,
You sound like you know exactly what your talking about, and say it with authority.
(You should be a "statesman", because the polititians do exactly the opposite.)

If it were me, I would heed Snowridge's advice.

 

[SnowRidge]

I just came across my PDF copy of the drive pump manual. Provided they are still using the same pump, which seems likely, the specs call for +/-15 degrees max rotation for the control shaft that is operated by the treadle.

The control shaft operates an internal swashplate that controls direction and flow of the pump's output. The manual states that the control shaft has no internal spring or other centering device, and that internal forces may move the control in either direction, therefore the control system must hold the swashplate control shaft at the desired angle.

I read that to say that a sloppy or loose treadle control could result in erratic operation.