My Van : 1992 E150, 300 straight six, E4OD

Problem: My power steering seems to be completely gone. I've had a fluid leak, which required me to top off occasionally. However, one day after a standard hard right turn about 4 months ago the steering gradually got harder and harder to turn the wheel in either direction, to the point that now it is gone completely. Fluid is and has been clean and present. When I have lifted the van off the front wheels, the steering is easy to turn (without the engine on).

How to I troubleshoot if it is just the leaky lines, ps pump or gear box ?

 

Replace the pump
Common on the GM Saginaw pumps to lose assist like that
The steering gear should be okay
Checking pump output pressure is pretty damn difficult using the special tools from the 1950's
I used to just crack a line and see if it would squirt you right in the eyes, that means the pump works and the gear needs overhauled / resealed
With the GM pumps on vans, the only lack of assist problems I sever aw were the pumps fault
Overhauled a whole bunch of gears in conjunction with the pump replacement, but it was the pump that fixed the van

 

Avoid the Duralast PS hoses from Autozone. Mine started leaking at the crimp fitting in just 3 years.

 

Thanks, trying to diagnose steering gear vs steering pump is what I was trying to figure out. I will try the simple straightforward test you mentioned.