Have you considered cutting out the rear of the tub on the PT-425?

[Kent]

Background info...my Robin EH72 wouldn't start and was popping flames out of the carb. After I ruled out all the usual problems I broke down and called the local Robin repair shop, which after an initial diagnosis of either a timing or valve problem, dragged the thing onto their trailer and took it off the shop. (After reading all the posts and trying various things I still can't find how to use the "tow valve" on my 2011 model, so it was a "man against 1200 lbs of dead weight" battle winching it up the trailer ramp).

It turns out the problem was a blown stator assembly...and due to the lack of clearance he couldn't remove the shroud or make the repair without pulling the engine. Not having worked on PTs before and me not knowing any better, he also felt he couldn't get the engine out without taking both pumps with it, so it was a big job that took 4.5 hours total. The bill was $409. (I have subsequently learned on this forum that it may be possible to just remove the engine.)

Before committing to removing the engine he was tempted to take a torch to the back of the tub and cut it off, replacing it with 1" bars on three sides and tapping bolt holes. Had the back of the tub been removable, the stator job would have taken him under an hour.

He also mentioned that the blower housing was clogged with grass (not visible from the outside) and perhaps that contributed to the failure. And when I asked how I could keep it clean, he could only come up with "pull the engine".

And of course having removed all the hydraulic hoses, the tractor came back with what I hope is just lots of air in the system, which I will bleed this afternoon. Right now the engine works great but there is almost zero power to the wheels, no reverse to speak of.

So his suggestion is to cut off the back of the tub and make it a bolt-on access hatch, which would make it easier to work on the tractor, and in his opinion, not sacrifice its strength.

Thoughts?

 

[J_J]

You should or must do an air bleed of the hyd pump, or damage will occur.

There is a tube that you put over the bleed ports.

Raise the 425 off the ground as you need to work the wheel motors.

Disable the engine run mode, and use only cranking speed to purge the air from the pump.

The other gear pumps should self purge as you use the cyl's.

 

[ponytug]

Not that I'm a structural engineer, but I wouldn't be wild about cutting the tub. To regain the lost strength probably involves the addition of some of the peripheral members.

Drilling a small access hole might be different. It depends on where you would need the hole.

You could add screening around the tube to reduce the amount of clippings entering the tub.

All the best,

Peter

 

[KMA]

The blower housing filled with grass might be from rodents/mice. I just had to clean grass nests out of my EH72 without pulling the engine and it was a nightmare. I can't be sure I've gotten all of it either.

I agree the design isn't ideal, not only for the difficulty in servicing the engine but also the way it traps heat. I'm still trying to work out high temp issues after my engine swap. I think I will build a custom exhaust next to see if that help reduce temperatures in the engine bay.

 

[washita]

The blower housing filled with grass might be from rodents/mice. I just had to clean grass nests out of my EH72 without pulling the engine and it was a nightmare. I can't be sure I've gotten all of it either.

I agree the design isn't ideal, not only for the difficulty in servicing the engine but also the way it traps heat. I'm still trying to work out high temp issues after my engine swap. I think I will build a custom exhaust next to see if that help reduce temperatures in the engine bay.

I would hesitate to cut out the rear of the tub, but I am constantly boring holes into the tub so I can access bolt heads when working on the engine and I will eventually build a better motor mount since mine likes to loosen up and allow the motor to move forwards and rearward I am positive that backing into a tree and destroying the muffler/exhaust has not helped the motor mount issue

 

[BobRip]

In case you don't realize it the tub is structural. Be sure you make the modification as stronger or stronger than the original.

 

[Kent]

Update: Subaru said they won't cover the cost of the repair because they see the problem was due to overheating. I am thinking about how to cut a hatch in the fan cover to allow me to clean out any grass. Ideas?

Background info...my Robin EH72 wouldn't start and was popping flames out of the carb. After I ruled out all the usual problems I broke down and called the local Robin repair shop, which after an initial diagnosis of either a timing or valve problem, dragged the thing onto their trailer and took it off the shop. (After reading all the posts and trying various things I still can't find how to use the "tow valve" on my 2011 model, so it was a "man against 1200 lbs of dead weight" battle winching it up the trailer ramp).

It turns out the problem was a blown stator assembly...and due to the lack of clearance he couldn't remove the shroud or make the repair without pulling the engine. Not having worked on PTs before and me not knowing any better, he also felt he couldn't get the engine out without taking both pumps with it, so it was a big job that took 4.5 hours total. The bill was $409. (I have subsequently learned on this forum that it may be possible to just remove the engine.)

Before committing to removing the engine he was tempted to take a torch to the back of the tub and cut it off, replacing it with 1" bars on three sides and tapping bolt holes. Had the back of the tub been removable, the stator job would have taken him under an hour.

He also mentioned that the blower housing was clogged with grass (not visible from the outside) and perhaps that contributed to the failure. And when I asked how I could keep it clean, he could only come up with "pull the engine".

And of course having removed all the hydraulic hoses, the tractor came back with what I hope is just lots of air in the system, which I will bleed this afternoon. Right now the engine works great but there is almost zero power to the wheels, no reverse to speak of.

So his suggestion is to cut off the back of the tub and make it a bolt-on access hatch, which would make it easier to work on the tractor, and in his opinion, not sacrifice its strength.

Thoughts?