1250 hydro problems

[MrRazz]

Originally Posted by Ambush

That does sound like the hydro failing.

I started at 1:00 and by 3:30 the whole thing was on the bench. I spent another hour cleaning the outside of the assembly. Takes another 15 minutes to take the head off to look inside. They are very simple and with care are easy to reassemble. You just have to use extreme caution not to bang, drop or scratch some of the intervals.

You won’t have to take it this far apart to find to determine if the hydro is shot.

So theoretically if it was failing, what would be failing? Is it a crap shoot until you tear it down or can you narrow it down better to the charge pump or the motor section or something else? I'm trying to learn about these and understand them better. They look fairly simple but I just don't have any experience with them.

[Ambush]

If the charge pump fails completely there won't be any "make up" oil to supply the pump and it won't move. Usually if the transmission is weak, it's because of damage to the brass port plate(s) allowing oil to bypass rather than build pressure. If the hydro is weak and noisy, I'd quit running it, regardless.

[MrRazz]

Originally Posted by Ambush

If the charge pump fails completely there won't be any "make up" oil to supply the pump and it won't move. Usually if the transmission is weak, it's because of damage to the brass port plate(s) allowing oil to bypass rather than build pressure. If the hydro is weak and noisy, I'd quit running it, regardless.

Are those parts "serviceable"? What causes the whine sound when under a load, I hear lots of tractors making that noise.

[Ambush]

For 99.9% of shops they are replaceable but not repairable. I spent the last 28 years of my working life in a hydraulics rebuilding shop. We had specialized equipment and process's to refinish many parts rather than replacing them. It was a niche specialty and saved our costumers, big and small, a lot of money and time. There is "hydraulic whine" but a rough whine is likely damage. And since you have whine and poor performance, that's a good indicator.

You can remove your charge pump after removing the driveline.

Tomorrow, I can takes some pics to indicate areas that usually wear. And they go downhill real fast.

[1711Cub]

With the vast supply of good used Sunstrand hydro units, I would not bother rebuilding the unit. I've rebuilt them, and they are pretty straightforward, but financially, you will be ahead just getting a good used unit and swapping it out. Just get a new cork gasket for the hydro to transaxle mating surface. These rarely fail, even being 30-50 years old.

[MrRazz]

Originally Posted by Ambush

For 99.9% of shops they are replaceable but not repairable. I spent the last 28 years of my working life in a hydraulics rebuilding shop. We had specialized equipment and process's to refinish many parts rather than replacing them. It was a niche specialty and saved our costumers, big and small, a lot of money and time. There is "hydraulic whine" but a rough whine is likely damage. And since you have whine and poor performance, that's a good indicator.

You can remove your charge pump after removing the driveline.

Tomorrow, I can takes some pics to indicate areas that usually wear. And they go downhill real fast.

Sure if you don't mind

[Ambush]

The most common failure is on the lens plates. Obvious scoring between the ports is easy to see. In the one pic, you can see a score line going from the pressure side of the pump the slack side, caused by contamination. In bad cases a large groove will join all the ports.

Notice the motor side has four V shaped notches and the pump
only has two. Sometimes there are scratches on the brass piston slippers too. That’s always from contamination.

[MrRazz]

Originally Posted by Ambush

The most common failure is on the lens plates. Obvious scoring between the ports is east to see. In the one pic, you can see a score line going from the pressure side of the pump the slack side, caused by contamination. In bad cases a large groove will join all the ports.

Notice the motor side has four V shaped notches and the pump
only had two. Sometimes three is scratches on the brass piston slippers too. That’s always from contamination.

Alright I think I'm starting to understand this now. So when there are grooves worn in between the ports the pressure bleeds from one port to another and makes for a loss of power?

[Ambush]

Originally Posted by MrRazz

Alright I think I'm starting to understand this now. So when there are grooves worn in between the ports the pressure bleeds from one port to another and makes for a loss of power?

Yes, that is it.

[MrRazz]

Ok so I got two valves from a buddy and put them into my hydro, no difference. I put my valves in his hydro, no difference. I found another unit from a 149 and purchased it. This will be my first time tearing this far into my machine. Any tips would be greatly appreciated. Also what should I use and what is the best way to clean up my new used hydro without getting any junk inside of it?