94 F250 5.8 power steering comes and goes
 

94 F250 with SAS 5.8 auto.
All stock.

Was out plowing in the last storm and I lost the power steering.
Thought maybe I lost the belt but nope, its still there.
Checked the fluid and all good. (It was high in the reservoir).
Kept plowing and the power steering came back.
Then throughout the night it would cut in and out.
Almost felt like it would get stuck and then release sometimes.
Belt looked fine and fluid did too.

Bad power steering pump?

The steering box was replaced two season ago. Maybe it is going bad?

I would hate to start replacing parts when they aint bad (They aint cheap).
Any ideas of how to diagnose?

does your power steering pump make that loud whining noise? I have a '97 f250 HD. Mine is so loud I can hear it even when Im just sitting at a stop light. I'm wondering if mine is close to failing. I replaced the fluid even though it has never gone out like yours has.

No noise
 

no noise and no whining.