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I have installed a hydro boost system in my 1939 Chevy , yes power brakes and power steering in one unit .
I am trying to find out the proper way to bleed this system . looking on the internet has not been a good idea . nothing is consistent

does anyone know the best way to bleed a hydro boost system ? thank you

The system should be self-bleeding. Cycling the steering lock to lock several times, and repeatedly applying the brakes should cycle any trapped air back to the reservoir in the pump. Once it appears that the systems are functioning properly, top off the fluid level.
Jerry

See if these hints and tips from Hydratech help...

https://hydratechbraking.com/braketech1.html

Manymiles: Are you asking about how to bleed the Hydroboost system (hydraulic, driven by a pump on the engine) or the brakes themselves?

hi Fibonachu . what has confused me in the many articals I have seen , to get the hydro boost system completely bled , do I turn the steering wheel right and left 5 time ?
or do I turn the steering wheel right and left 5 times ?
do I pump the brake pedal 3 times after turning the steering wheel 5 times ? or do I pump the brake pedal 5 times after turning the steering wheel ?
is this done with the engine off or engine running ?

I have bled the brake fluid , using a vacuum system . I had seen articales where they did the turning of the steering wheels and pumping the brake pedal up to 90 times ????

thank you for you reply

If the brakes are properly bled first, and you have a firm pedal without the engine running, then purging the hydroboost/power steering system is usually pretty simple. Don't be concerned about how many times to turn the steering wheel and or pump the brake pedal. You'll know when you're done. When purging it, it helps to have the engine at a bit over idle speed. Also possibly helpful if the purging process still results in a brake pedal kickback indicative of air in the system, is applying a vacuum to the reservoir cap.

The GM Techline instructions say to fill the power steering pump reservoir to the cold mark, start the engine, and firmly/fully apply the brakes 10-15 times.

Shut off the engine, check/fill the power steering reservoir back to the cold mark.

With the engine off, lift the front axle off the ground and turn the steering wheel lock to lock 15-20 times.

Check/fill the fluid.

Start the engine and slowly turn the wheel lock to lock twice while listening for signs of air pockets/cavitation (pump noise/whining).

If there are signs of cavitation, repeat the bleed process. If there are still signs of cavitation, inspect hoses and connections for leaks.

I also found doing this with the Tires OFF on these older trucks allow you to go to full lock to lock on these systems. With my wider tires I never got a full lock to lock turn on the steering wheel.
But the above gm process is what i do anytime a any of the Hydro boost parts are worked on

That is a very good point. You need to go full lock on the *steering box*, not the *tires*.

Depending on how the stops on the spindle are adjusted on the truck, they might clip before the steering box.

It would also be possible to disconnect the tie rods at the spindles- - - -which would guarantee that the rack travels fully lock to lock!
Jerry

Drag link works too only one disconnect point.