How to replace master cylinder. what is the relationship between it and the power steering?

The slash that you placed between the words steering/brake have me concerned. I certainly hope you did not think that these two systems are co-joined? The power steering system is a hydraulic system completely separate and isolated from the brake system. They also use two completely different types of fluid. Putting brake fluid in the power steering system would destroy it just as putting power steering fluid in the brake master cylinder will destroy it. The type(s) of rubber used in the seals for each of these systems demands they use their own fluid. Any cross-contamination will require a complete draining, cleaning, and replacement of ALL rubber components and seals. This would include the power steering pump and rack for the power steering system, and for the brake system the master cylinder, all calipers and wheel cylinder as well as the proportioning valve. If there is an ABS unit, it will need serviced as well.

Hello Patricia,

Have you checked the master brake cylinder reservoir for brake fluid loss?

I don't suspect the master cylinder as you have replaced it... but am more suspect of a leaking brake line or fitting which should have
been discovered when you had the system bled.

The only time I ever had a rear brake problem with a 2500 series Chevrolet was due to seized rear brake caliper guide pins...as your calipers are also new that is not your problem.

If your brake pedal feels spongy and travels to the floor board you have air in the system, a brake fluid leak or a failure in the power steering system, such as a broken hose, broken power steering pump drive belt, or failed pump, would result in a loss of pressure to both the hydro-boost and steering.

Find more information here:

. Hydro Boost Power Assist Systems Operation Diagnosis and Repair

now the question is
did you get the original master cylinder as a replacement or did you get a new master cylinder for the car that the callipers came off
understanding that there is a direct relationship between master cylinder piston size and calliper piston size, you problem appears to be that there is not enough surface area in the master cylinder to effectively push the calliper pistons out to apply the correct braking pressure
mixing and matching with brakes requires a lot of hydraulic knowledge and pressure differences which include fitting a proportioning valve in the rear brake lines to prevent brake lock up at the rear wheels

Lingo is o.k., but I think you may be confusing power steering with power brakes. Power steering has no master cylinder (brakes do) and no power booster (brakes do). The power steering pump is mounted on the front of engine and run by the fan belt or the serpentine belt. The p/s hoses are 2- a pressure line and a return line, and run from the pump to the steering box or to the rack and pinion steering gear.
It just sounds like you have a brake fluid leak at the master cylinder. If it is, you need a new or rebuilt brake master cylinder.
Good luck. Post back for more.

The rear seal of the master cylinder plunger is leaking, you must replace the master cylinder to correct this.

are you talking about brake fluid --power steering lines do not connect to the brake system --- also their is no weep hole at the bottom of the brake booster ---can you please clarify what is leaking and where --power steering lines from pump to radiator to steering rack ----brake booster mounted to fire wall with brake master cylinder bolted to front

no relationship between these 2 issues. Check the flasher unit under dash, driver side of steering column, mounted on support bracket

Check the power steering fluid level.Allso check the master cylinder level.Witch ever is low is your problem k

if you got the hydro brake boost system .check your power steering pump hoses for leaks .check master cylinder is leaking. fill power steering pump and master cylinder with fluid. the one that is the lowest that the one leaking. if your hydro boost brake unit is leaking .replace it .if power steering pump leaking. it not the hoses replace it . because if power steering goes out brakes will also go out.

yes they both run threw the hydro booster attached to the back side of the master cylinder! if your vehicle is a 2500 model