rthompso

1997 Suburban, lost power steering and brakes. Changed power steering pump, no change changed hydro boost, no chance. cycled steering side to side, not running and running, no change. checked lines for flow, all good.
What kind of pressure should I be getting from pump tp hydro boost?

Suburban Dude

It’s possible you did the the side to side air bleed procedure too quickly. According to some sources the procedure to bleed is to jack the frame such that the front wheels are off the ground. Center the wheels. With the engine running, move the steering wheel a half inch to the right, back to center then a half inch to the left. Keep doing this in 1/2 inch increment each time, until you are finally going lock to lock. The instructions say you must do this very slowly such that the entire procedure takes about a half hour. Meanwhile top up the power steering fluid as it drops.

Please let us know if that helped .

SD

Rednucleus

Curious, did brakes & steering go out at same time or has this been an ongoing problem for you. More history please. BTW how's it running otherwise?

rthompso

History of the power steering being a little stiff, showed up more so at low engine rpm, got worse until I lost both P/S and brakes. Didn't notice any brake problem until the end.

rthompso

No joy, did the procedure twice, no change, still no power assist to brakes or steering.

Suburban Dude

See if you can dissconect the return line from the hydro boost, connect a rubber hose to a jar and flush the hydro boost unit, keeping the power steering fluid topped up.

If that doesn’t work, It’s possible there is a bad seal inside the hydro boost unit itself which would require rebuilding or replacement.

SD

Suburban Dude

Search brakeandfrontend hydro boost for a good article on bleeding a hydro boost. Let us know how things turn out.

SD

Suburban Dude

Lastly, when you get the problem solved, might be a good idea to grease all the steering grease points and don’t forget the one on the idler arm bracket. This might reduce the steering effort. Just guessing on this one.

SD

Suburban Dude

Spent a bit of time tracing the high pressure line from the power steering pump. It travels directly to the hydro boost unit and then there is a high pressure from the hydro boost unit to the steering gear. Certainly if something is amiss with the hydro boost unit, it will affect the power steering. (As if we didn’t already know that.) Anyone else out there with some advice on how to properly bleed the hydro boost?

SD

Suburban Dude

One more thing. A posting in Duramax suggested when bleeding the low pressure line from the hydro boost, you need to press the brake pedal down, turn the steering wheel from 12 o’clock to 3 o’clock, then slowly release the brake pedal. Then you turn the wheel back to 12 o’clock and then repeat. Not sure if this is going to be effective but probably worth a try.

SD