Oil leak - older PT425 60” finishing mower

   / Oil leak - older PT425 60” finishing mower
  • Thread Starter
#11  
The oil appeared to be originating from the hydraulic motor, so I went ahead and ordered the replacement.

Haven’t decided whether to replace it myself or have it done. Is there any special priming/bleeding procedure or is it just plug and play?
 
   / Oil leak - older PT425 60” finishing mower #12  
The oil appeared to be originating from the hydraulic motor, so I went ahead and ordered the replacement.

Haven’t decided whether to replace it myself or have it done. Is there any special priming/bleeding procedure or is it just plug and play?
I don’t think there’s anything special about replacing the hydraulic motor on the mower. I’d probably try and elevate the old motor so the hoses are hanging down with the couplers on the ground. Then disconnect the hoses from the old motor and keep the open ends elevated. Then I’d probably put some oil in the new motor ports and spin it over by hand a few times and then reconnect the hoses. Then connect the male and female quick connects together and spin the motor some more by hand. That’ll circulate oil through the motor and hoses. Yes, there’ll be a little air in there, but it won’t hurt anything.

Put the motor back on the deck, hook it up to the tractor, start the tractor, and at low RPMs, turn the PTO switch on and that’ll bleed any air almost instantly, as new fluid will push through the hoses and motor and back into the tank ASAP.

Someone correct me if I’m mistaken, thanks.
 
   / Oil leak - older PT425 60” finishing mower #13  
I'm a fan of not adding unfiltered oil to motors. I saw a report once on how much debris on average is actually in a new can of oil, and it put me off the habit. (I do fill filters, but only in the direction of the oil, never any dirty oil on the "wrong" side of the filter. Things may have improved in the last decade, but if it were me, I would pass on adding oil.

I would clean off all of the motor fittings and the entire area round the motor that you might touch (power wash, blow off with air, then repeat cleaning with brake cleaner, wipe with clean towels and repeat until no more dirt appears, then open the threads a little and repeat the brake cleaner). Terry once commented that working on motors needed to be heart surgery clean because anything that gets in to the motor is recirculated for a long time in the motor circuit. The advice stuck with me.

I bought a nice set of JIC metal plugs off of Amazon, that I find quite useful for sealing loose hydraulic hoses ends as soon as they come off, unless the hose is going on the next item immediately. Personally, I prefer to transfer the hoses one at a time as I loosen one hose from the old motor, remove the hose, and move it to the new motor. Fewer opportunities for me to do something dumb like swapping hoses onto different ports. Labeling the hoses before you start helps, too.

Once you power the tractor up, the motor pressure will basically go from 15psi to 3000psi as soon as you pressurize the motor, and the air volume will collapse to a tiny fraction of itself, (0.5%) and as oil bleeds out of the motor system, the dissolved air will be carried off to the tank. The air in the motor circuit may/will make the motor response "spongey" for a little while, so my two cents is to plan your stops with lots of room for delayed response until you get the hang of the delay in the pedal response. It gets better with motor use; in my experience, pretty quickly.

All the best,

Peter
 
   / Oil leak - older PT425 60” finishing mower #14  
I’d agree with you on the wheel motor circuit. However, the PTO pumps that power the mower deck, steering, FEL and quick attach are not filtered. Only the oil going into the variable volume pump to supply the charge pump is filtered. So adding fresh unfiltered oil to the mower motor wouldn’t concern me.

I will agree with you that cleanliness is imperative though. So clean everything thoroughly before removing hoses, fittings, etc. and keep any open hoses plugged if it’s going to be open for more than a few moments.
 
   / Oil leak - older PT425 60” finishing mower
  • Thread Starter
#15  
Great advice guys! I will post how it goes. Hopefully it won’t take me too long to get around to it.
 
   / Oil leak - older PT425 60” finishing mower #16  
Speaking of hoses… never be tempted to disconnect a hose and lean it against something while you do something else. Always cap it and secure it if you’re going to be distracted. There’s a few horror stories of people leaving disconnected hydraulic hoses unattended, the hose end falls lower than the tank, and 10 gallons of motor oil is then on the floor/ground.

Just something that I’ve always kept in the back of my mind once I heard one of those stories here on TBN. ;)
 
   / Oil leak - older PT425 60” finishing mower #17  
It wasn't a full 10 gallons, there was still some left in the tank. 🙃

Like everybody says, clean clean clean. I'm thinking that air will purge almost immediately like on the order of .5 seconds.
 
   / Oil leak - older PT425 60” finishing mower
  • Thread Starter
#18  
Quick update: I replaced the motor and all seems well now. The hardest part was removing the lovejoy fitting from the old
motor shaft. Wouldn’t have been hard if i had a vise setup or proper tools.

Thanks for the advice everyone.
 
 
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