425 stopped going

dbetts · Jan 16, 2005

I'd like some advice about where to begin looking for the reason my 425 won't go. It was working fine yesterday, but when I started going on it today it quit moving. The engine works fine. Steering and loader hydraulics work fine. The peadal feels normal but when pressed either direction the tractor does not move. I raised the front wheels off the ground by lowering the bucket and the wheels will move very slowly in the proper direction when the pedal is pushed, but without enough power to move the tractor.The hydrauic fluid level is correct. I don't see any fluid leaks. I'll call Terry tomorrow, but in the meantime I'm very greatful for any suggestions from the brilliant and wise PT users on this forum.
db

Bob999 · Jan 16, 2005

Two possibliities come immediately to mind:

The towing port is open--which bypasses flow that would otherwise go to the wheels;

or there is a "break" in the link from the treadle to the connection at the variable displacement--check ( you will probably need a helper) that when you move the treadle it actually moves the lever on the variable displacement pump.

pequeajim · Jan 16, 2005

I know this is silly to comment, and you already said that your wheels move a little but is the parking brake on? /forums/images/graemlins/blush.gif

Clarke · Jan 16, 2005

Follow the hydraulic lines from the treadle to the pump. the fitting on the pump these are connected to have a small orifice which may be clogged, Just remove the hose then the fitting and check the orifice. Also check the treadle and make sure the cap screws that hold it on are tight. If these are loose the treadle will be very floppy. Check or even change the hydraulic filter. Could be pump failure.. I am assuming you have a newer PT with the hydraulic tram circuit.
Please let us all know the final outcome and good luck.

sg /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif

MossRoad · Jan 16, 2005

Sorry to hear of your troubles. Just remember, if you pull any hoses having to do with the drive system, you should bleed the pump as instructed when you do the filter change, just to eliminate the possibility of killing the pump with air bubbles.

On our PT425 there are two hydraulic pumps. I believe the steering, lift and aux. PTO (quick attach circuit) all run off of one section of the first pump. The second section of that first pump is for the main PTO. Then we have a seperate, variable volume pump in front of our engine that provides the power to the wheels.

I believe your PT425 is set up with the same arrangement of pumps, except all of your pumps are in front of the engine. Same functions, though.

Since your steering and lift arms work, I'll bet your main PTO works, too. So this leaves you to diagnose the variable volume pump and the drive circuit.

Our PT425 has a cable that runs from the treadle, through the tunnel to a lever on top of the variable volume pump. I think yours is new enough that you do not have this arrangement. You probably have the treadle that is attached directly to a hydraulic valve under the center hump between your feet.

Good luck with your phone call, tomorrow. Please let us know how it turned out.

dbetts · Jan 17, 2005

Well now I feel stupid, I went back out several hours later and it worked fine. I've used it before in the cool weather (about 30 degrees) without problems but I wonder if the fluid was just too viscous to flow correcctly so soon after just starting it up. Thanks for the input and I'll let you know if it does it again .
db

MossRoad · Jan 17, 2005

That's odd. Mine will move after a cold start in cold weather, just not real fast. The lift and steering are very stiff. When it is below 30, I usually start mine, double check the parking break by stepping on the forward AND the reverse direction pedals to make sure it is engaged, check all implemements down and let it run at 1/4 to 1/3 throttle for about 5 minutes. Just the fluid circulating through the pumps for that long is enough to warm it up so everything moves normally. When it gets down under 10, I have to let it run a little longer. This usually gives me just enough time to sweep the steps and small walkways. When I get back, the PT is warm and ready to go.

Just keep an eye on things and see how it goes. Just curious... did you have it at full throttle when it would not move or were you at a low throttle setting?

Rick_Taylor · Jan 17, 2005

If it stops again, check to make sure the VV pump is actually turning. I don't know how much you can see in your configuration. I have an older unit with pumps at each end of the motor. It did exactally the same thing as yours, just quit moving. All other functions OK. Turned out to be the Lovejoy coupling between the engine and pump had worn and then broke. One half of my coupling was steel, the other half was aluminum! Duh! It was a &*%#$@ to change. What I found was that the steel key had moved and broken. Seems someone at PT had forgotten to put in the two setscrews holding the coupler half to the motor shaft. One of those screws holds the key securely down in the shaft keyway slot. The replacement coupler was also aluminum, but this one isn't going to move. I put two setscrews in each hole with a LOT of anti-sieze. The PT has almost 200 more hours on it now with no problems.

dbetts · Jan 17, 2005

I'll hopefully have a chance to work a little bit outside tomorrow. To answer a couple of questions, the parking brake is not engaged. I always run at full throttle, the main reason is that on my hill I am routinely going up a slope that requires full power. We'll be down to 14 degrees tonight so we'll see how it does in the morning. Thanks again to everyone for the help . Rick, thanks for recounting your troubles, hopefully I won't meet the same problems with my current issue. db