Hydraulic pump won't prime

[86LG4T5]

Ford 3000. Hydraulic was very weak so I rebuilt the pump. Works great. For about a week. Then blew the gasket in the cap and leaked a lot of fluid. So I pulled the cap and replaced the gasket. Replaced a couple of ball cages that were bent too. Reassembled and now the pump won't prime. Tried compressed air and fluid starts coming out weak, but as soon as you stop the air, the fluid stops. Any ideas?

 

[damn1981]

Sounds like balls are not seating so won't suck did you change out plates also

 

[86LG4T5]

Yes I changed the plate when I rebuilt it. After I rebuild it everything was fine until it blew the gasket in the cap. I guess I didn't tighten the cap bolts enough. Anyway, now that I've re-replaced the cap gasket it won't pump.

 

[86LG4T5]

There's a philips screw that holds the plate on. I tighten it as hard as I can but when I remove the cap it's not that tight. Not sure why they would use a philips instead of a bolt if they wanted it really right?

 

[damn1981]

Are the plungers all free springs did not collapse

 

[Btzj02]

There's a philips screw that holds the plate on. I tighten it as hard as I can but when I remove the cap it's not that tight. Not sure why they would use a philips instead of a bolt if they wanted it really right?

After working on my pump I am thinking that screw is only for holding the plate while assembling the pump. Once the pump is assembled that screw doesn't really do anything.

 

[Mike(NEOhio)]

After I rebuilt mine it took a while to get all the air out of the system. I thought it was OK but still would not lift well. I plumbed a length of clear tubing from the bleed port of the pump back to the fill port. It looked like solid fluid till I shut it off and saw half-inch bubbles in the hose. I let it idle for a while and after about 20 minutes it was good.

 

[86LG4T5]

Are the plungers all free springs did not collapse

Yes the 6 pistons and those large springs that go on them are all fine. I honestly don't understand what the balls in the cages do. A couple of the cages in the cap had come out part way and a couple of them had a bent leg.

 

[Keith Williams]

Yes the 6 pistons and those large springs that go on them are all fine. I honestly don't understand what the balls in the cages do. A couple of the cages in the cap had come out part way and a couple of them had a bent leg.

The balls in the cages are check valves.
As the pistons move forward, the fluid is pumped out past the balls. When the springs push the piston back, the ball is pushed onto it's seat by the cage thing and new fluid is brought into that chamber from the rear of the tractor. Then the cycle happens again.
HTH
Keith

 

[Mike(NEOhio)]

Yes the 6 pistons and those large springs that go on them are all fine. I honestly don't understand what the balls in the cages do. A couple of the cages in the cap had come out part way and a couple of them had a bent leg.

The legs of the cages need to be straight enough for the balls to be free to move. The rebuild kit I used had new cages but they were softer than the originals. The cage legs will protrude a bit above the surface and need to fit into the counterbore. If not the cage will distort and pinch inward so the balls can't move to seat. I had to take it apart again and straighten them with pliers.

 

[86LG4T5]

The legs of the cages need to be straight enough for the balls to be free to move. The rebuild kit I used had new cages but they were softer than the originals. The cage legs will protrude a bit above the surface and need to fit into the counterbore. If not the cage will distort and pinch inward so the balls can't move to seat. I had to take it apart again and straighten them with pliers.

Mike this is really interesting to me. Maybe you could explain it a little more? The most recent kit I bought to get the gasket I needed included new balls and cages and those tiny cone springs. There were 3 cages with a bent leg. I don't understand why. I replace them with cages from the newest kit and they are much heavier and a little longer. They stick out a little further. Do they need to sit flush? It seems like they're slipping out.

 

[Mike(NEOhio)]

Mike this is really interesting to me. Maybe you could explain it a little more? The most recent kit I bought to get the gasket I needed included new balls and cages and those tiny cone springs. There were 3 cages with a bent leg. I don't understand why. I replace them with cages from the newest kit and they are much heavier and a little longer. They stick out a little further. Do they need to sit flush? It seems like they're slipping out.

Been a few years since I did mine, going on failing memory. Mine was malfunctioning in cold weather, chattering on lift or no lift at all. It still did it after I went through the lift so I went to the pump. The kit had new balls, cages and ball seats. The legs of cages protruded, maybe 1/32 or 1/16. On assembly it was a bit stiff when I put the bolts in. Didn't feel right so I took it back off and found the legs were partly crushed. I had to straighten them. They need to go into the recesses in the plate (key 35) in the circled areas. The balls and seats looked OK to me but after I put the new ones in it has worked perfectly ever since. I think the inlet valves were the problem. If the ball gets caught in the cage the spring isn't enough to push it back into the seat