Power Steering failure

PROBLEM with power steering
1991 Chevy 545 in a Bounder. Power steering makes a howling noise. Fluid level full when engine is NOT running. After howling a while the power steering is lost and the fluid is full of bubbles and squrting out overflow tube. Breaks are also sharply effected.
Power Steering failure

Don, I don't know about Chevy but on the early 90's Fords when the power steering fluid gets low it also affects the brakes. In your case there would be air in the brakes. I am with Butch, try a new pump and at the same time have the vacuum booster on the braking system checked.