Hydraulic Pump = PIA

[flyingace]

I just replaced the oil seal in the Hyd pump of my Ford 3000. Now, every time I start the tractor, the lift arms won't lift. If l I bleed the pump, everything is OK. It will continue to work OK as long as I don't let it sit too long. BTW, this is a piston type pump.

Is air getting into the pump from someplace or will this go away eventually?

 

[steve n carol]

The suction/supply line to the pump, (about 7/8" dia) is a slip fit held (partially) in place with a 'square cut', "O"-ring. This is prone to "sucking air".

There is much in the archives about this. It is recommended that the FORD "O"-ring be used here. If my memory serves me right, there is another one at the other end of this steel pipe too.

Perhaps you can slather grease around this to check for an air leak ...sl

 

[flyingace]

The suction/supply line to the pump, (about 7/8" dia) is a slip fit held (partially) in place with a 'square cut', "O"-ring. This is prone to "sucking air".

There is much in the archives about this. It is recommended that the FORD "O"-ring be used here. If my memory serves me right, there is another one at the other end of this steel pipe too.

Perhaps you can slather grease around this to check for an air leak ...sl[/quote]

Thanks for the reply and I'll check this out.

I've found that if I start the engine and let it run a couple minutes, the lift starts to work. Does this make a difference in the diagnosis?

 

[steve n carol]

The suction/supply line to the pump, (about 7/8" dia) is a slip fit held (partially) in place with a 'square cut', "O"-ring. This is prone to "sucking air".

There is much in the archives about this. It is recommended that the FORD "O"-ring be used here. If my memory serves me right, there is another one at the other end of this steel pipe too.

Perhaps you can slather grease around this to check for an air leak ...sl[/quote]

Thanks for the reply and I'll check this out.

I've found that if I start the engine and let it run a couple minutes, the lift starts to work. Does this make a difference in the diagnosis?[/quote]

Ace, if you let it sit awhile....... I am thinking gravity draining off the supply line. .....
Assuming that the HYD fluid level is correct. The LOWER "O" ring (on the supply tube), which is down by your right footrest, would be lower than the fluid level itself, and would (probably) leak while sitting. this points, again, to the top "O" ring, at the pump.


"I've found that if I start the engine and let it run a couple minutes, the lift starts to work. Does this make a difference in the diagnosis?[/quote]

Sounds like this is bleeding out the air in the system.

In another recent post, there was a crack in the cast iron piece that was causing a leak, I think that was a fluid leak. Similar symptom.

So you check one problem at a time... Enjoy these days while we can...sl

 

[Dean]

The pump appears to be loosing it's prime, and this symptom will not go away without attention.

As previously suggested, replace the O rings at the connections with proper CNH O rings.

If this does not solve the problem, disassemble and inspect the pump.

Dean

 

[steve n carol]

If i recall, the gaskets on the pump are directional. DON'T ask me how I know this.... :lol:

If you R&R this pump, look for that.....

Dean, do you think he could be loosing his prime at the shaft seal inside the pump, the one dear the bearing?...sl