Pump loosing prime

[dmbinva]

I have a 640 that is giving me a fit. I have rebuilt the pump. You can bleed the pump and the loft will work. let the lift back down and you have to bleed the pump again.
David

 

[showcrop]

I would be taking my manifold off and replacing the O-rings with the genuine CNH rings.

 

[dmbinva]

I used Case/IH O rings and the square ones are where they go and the round ones where they go

 

[pomester]

there is an early model and a late model bearing mechanism associated with the nose/drive end of the hydraulic pump - the early style used a doubled ball bearing design and is prone to leaking air/losing prime -

the early style isn't serviced so if that's the problem you are looking at finding a different pump to deal with the issue -