My Naa is loosing pump prime

[oldtimememories]

Hi there, new here. My boyfriends 54 NAA will not hold prime on the hydraulic pump. We got this tractor a while ago, and when trying out a back blade, hit a rock and after the lift would not work. Decided to do a refresh on the pump and lift cylinder. ALL new parts in the pump which works great after I let the air out of the bleed port. New bearings, seals, wobble gear, gasket, springs,etc. Only the pistons, wobble bearing and housing is old. New piston on the lift. Found the floating valve in the lift stuck, probably from the rock hit. Can't remember it's name of hand. Bleed the air for a moment and the lift is fine. New seals on the inlet and outlet of the pump. I don;t have a service manual , so thought I'd ask you guys. Rachel.

 

[Cliff(VA)]

My NAA was losing prime though pitting on the shaft. Was the shaft nice and smooth with no pitting?

You have a leak somewhere that is letting air in. I would check all of your connections and everything you have touched.

HTH

Cliff(VA)

 

[oldtimememories]

I rechecked 3 or more time already. New wobble shaft too. I know I have an air leak, but how do you find it??

 

[oldtimememories]

Took the pump off again and and blew compressed air into the pressure port. Air leaked slowly from the input port, so I took the top off the pump and found air leaking around the center bolt that hold the middle plate. Will try to figure a way to compress it better. Not sure if this is the problem or not.

 

[oldtimememories]

I have to say why bother posting as no one gives a hoot to help

 

[Kurt-NEPA]

Sorry to be late chiming in.

It sounds like you have a round piston pump from the hundred series tractors on your NAA. One good way to check for an air leak is to plumb in a clear tube from the bleeder port on the pump back to the fill opening under your seat. Then start your tractor. You should see oil moving through the clear tube. If you see air bubbles, you have an air leak.

Let the tractor run for a while and see if the air bubbles disappear. and then let it sit overnight and try again. It the bubbles are back, it is a sure sign of an air leak in the pump. The usual source is the wobble shaft seal and the condition of wobble shaft where the seal rides.

This doesn't work if you have the original square vane pump.