old ford power steering mystery

Heres the challenge. 79 ford 400m, a/t. Power steering pump has been upgraded to an "extra duty" saginaw style pump. Started to get loud, then power assist in only one direction, so I drained the pump, replaced the pressure side hose, blew out the pump itself (perfectly clear), and checked for obstructions in the return line (none). Pump then worked good until I shut the truck off and all the p/s fluid is immediately pumped out the resivoir. So, I changed the pump and guess what,,, still does it. Nobody I talk to has heard of this and im wondering if I need a new steering box or what.. Any and all replies are greatly appreciated!

Heres the challenge. 79 ford 400m, a/t. Power steering pump has been upgraded to an "extra duty" saginaw style pump. Started to get loud, then power assist in only one direction, so I drained the pump, replaced the pressure side hose, blew out the pump itself (perfectly clear), and checked for obstructions in the return line (none). Pump then worked good until I shut the truck off and all the p/s fluid is immediately pumped out the resivoir. So, I changed the pump and guess what,,, still does it. Nobody I talk to has heard of this and im wondering if I need a new steering box or what.. Any and all replies are greatly appreciated!
Sounds like youve got air trapped in the system. The new pump should have come with instructions on their recommended procedure for bleeding the air out. Look in the reservoir with the engine running, after turning the wheel from side to side. If the fluid is foamy, or has air bubbles, repeat the procedure till the fluid is clear of bubbles. Good luck.
Later
Ed
.

Heres the challenge. 79 ford 400m, a/t. Power steering pump has been upgraded to an "extra duty" saginaw style pump. Started to get loud, then power assist in only one direction, so I drained the pump, replaced the pressure side hose, blew out the pump itself (perfectly clear), and checked for obstructions in the return line (none). Pump then worked good until I shut the truck off and all the p/s fluid is immediately pumped out the resivoir. So, I changed the pump and guess what,,, still does it. Nobody I talk to has heard of this and im wondering if I need a new steering box or what.. Any and all replies are greatly appreciated!
Sounds like youve got air trapped in the system. The new pump should have come with instructions on their recommended procedure for bleeding the air out. Look in the reservoir with the engine running, after turning the wheel from side to side. If the fluid is foamy, or has air bubbles, repeat the procedure till the fluid is clear of bubbles. Good luck.
Later
Ed
.