Hydro Gear 150071 center section wear

[lee]

After shearing off one of the torx bolts I managed to open up this unit and found grooves that will catch a finger nail on the aluminum center section pump block mating surface. There are 3 wear circles on this surface. The 2 wear circles on either side of the oil slots are pretty smooth and do NOT catch a finger nail. The larger wear circle on the outside perimeter is where the grooves catch a nail. Likewise on the steel pump block the 2 inner wear surfaces are smooth. Only very slight grooves that can be seen but don't not catch a nail are present on the outer wear surface. Question 1: Does a grooved outer wear surface mean this center section is toast? Question 2: I see the commercial units using this pump block have a steel valve plate part # 51444 that the pump block rides on. Could the surface of the aluminum center section be machined down the same thickness as the valve plate allowing the valve plate to be installed on this center section? If so the center section would be better than new. This center section part # 70250 is $150+ so if repair is possible with a $25 valve plate and some machining that might be a cost effective repair. What do you think?

[okie]

Welcome to the forum Lee. I am not smart enough to answer your questions but maybe someone will be along shortly to help.

Okie

[bgsengine]

1) Any grooves in the mating sections of the pump or motor rotors mean the thing is toast.. (both mating surface should be an almost mirror-like finish) - only very slight wear patterns typically from heat differences in the oil and contact of the mating surfaces)

many moons ago when we worked on a lot of Sundstrand Hydros (similar Piston-Block-Slipper Plate construction) they rode on slipper plates similar to what you describe (your $25 plates, nut they were steel with a thick bronze face, which was the surface we'd polish down) and we'd be able to rescue those units with some elbow grease and extra fine 800 grit wet-dry sandpaper on a 1/2" thick sheet of glass along with a bowl of water and polish them back to mirror smooth finish (but back then, labor was cheap)

However, once you pay the machine ship to machine down your $150 center section to take a plate that might or might not work (Same Size? Same diameter holes and slots, drilled and cut at same angles?) you've already spent more than the whole hydro unit is worth, most likely (unless your machine shop will work for free)

[KE4AVB]

Agree with with BGS on this.

Hydro Gear 150071 (319-0650)

First yes the center section as is in current condition is toast.

Of the images of center section I can find I don't find any mounting holes that would allow you to securely attach that plate. You may be able to machine it down if the plate you referring to fits the mount area and that it can be secured in place. This depend as much material is there to work with.

You need to in account the overall cost of this. For most us here the cost machining would about as much as the center section if not more plus there a need for additional part now which adds to this cost. This would be something I would need to send out to even have done here especially on an one time job. Even after machining that center section would need to cleaned very well as you don't anything left behind that could cause your problem again. Personally I would just bite the bullet and replace the center section.

And top this you still may end up having to replace that steel pump block too. All depends how well it preforms after the unit get up to operating temperature.

[lee]

Thanks for the welcome Okie! Glad we can confirm the center section is bad. That same 5 piston 10cc pump block is used on a lot of zero turn pumps but the 51444 valve plate is used between the pump block and center section. They cheapened the residential grade hydros by eliminating the steel valve plates. On commercial equipment you change the valve plates and motor and pump blocks instead of replacing the center section. Since you have a steel pump or motor block riding on a steel valve plate they last a lot longer than steel riding on aluminum. It's been a while since I got a quote from a machine shop so I'm sure you all are right that the cost of the machine work and new valve plate would exceed the cost of a new center section. This hydro is just a spare. I might just put it back together and set it on the shelf in case I need a part for one of my other hydro transaxles.