Can't get brakes to bleed please help

[Stroker-ace]

I hav switched over from powermaster to vacuum brakes. Here is what I have replaced:

Blazer front brakes with new calipers and hoses
Master cylinder
Booster

Do I need to change the proportioning valve too?

I can't get a solid stream of fluid out of my front brakes, I keep getting air no matter what: I've already replaced the master cylinder twice to no prevail. Even with a vacuum pump I still get a ton of air and I've been through 4 big bottles of brake fluid.

Please help I'm going insane

 

[steve hughes]

Did you bench bleed the master cylinder first?

 

[charlief1]

Is it a new or rebuilt unit. I've had a lot of issues with remanned units and won't use them any more.

 

[Stroker-ace]

No I did not bench bleed the unit: but after the amount of fluid I have put through it, it should have been ok by now.

And the unit is re-man as far as I know.

 

[charlief1]

Well the fact that you didn't bench bleed it and it's a reman is probibly the problem. Take it back, get a new unit and bench bleed it before you instal it. This should solve the problem.

 

[Stroker-ace]

ok, so the auto parts store cant get mne a new unit until tomorrow.

so for the meantime, we discovered one of my wheel cylinders is crap

So we are going to change both rear wheel cylinders, and I am going to bench bleed the master cylinder again to rule out the possibility of that being the source of air in the system.

Now what about my proportioning valve? if that was bad, would it cause air in the system??

 

[Chuck Leeper]

Had same problem on the vert.. Until we bench bled the m/c.. no pedal. We used a little hose and fitting deal that came with another m/c, and bled it on the car. Hooked up the lines... bled n/p.
Prop valve will not intro air.

 

[Danno]

You can narrow down the problem by cracking the line on the master when you pump it up. If it shoots out fluid then you know the master isn't the problem. Then check for fluid at rear and then front. If you have fluid at one and not the other you can narrow it down even further.

Note- you can pinch off flex lines to eliminate brakes to see if it makes a difference (there is a special tool for that, if you use vice grips make sure they aren't overly tight and I would put a peice of rubber hose on each jaw.)

 

[steve hughes]

If you don't bench bleed the master you ain't gona get no brakes.

 

[hemi8]

I bench bleed in a vise with a big phillips head screwdriver, the last one I did I pushed in and out for about an hour and 1/2. Be patient, no air bubbles AT ALL are allowed. Really push it hard till it bottoms out, slowly. The master cylinder should come with fittings and hoses to bench bleed. You will be surprised how long it takes before there is no air bubbles, usually there is 1 air bubble per push and this can go on for up to 400 to 500 pushes. Do not let the fluid go dry in the master cylinder or you will have to remove it and start over. Take the time and you will have the best brake pedal you have ever felt. Rebuilt is fine.
There is also a valve on the proportioning valve (on the front) that has to held in with a C-clamp, if it pops out you have to start over (do a search on this). MP brakes sells a part that screws into the prop. valve to eliminate the need to C-clamp the factory valve. You only need to change the prop. valve when you make a change like front disc and rear disc. If you still have front disc and rear drum you will be fine. If your valve is OEM and is 25yrs old, well, might be a good time to install a new one. MP brakes sells new ones. If you install a new prop. valve soak the fittings in WD-40 and use only super high quality line wrenches to loosen the fittings or you will be replacing all the brake lines as well. Don't rush it.
Disc Brake & Brake Conversion Kits, Suspension Kits: Master Power Brakes.
Mike

 

[1quick6]

There is also a valve on the proportioning valve (on the front) that has to held in with a C-clamp, if it pops out you have to start over (do a search on this). MP brakes sells a part that screws into the prop. valve to eliminate the need to C-clamp the factory valve. Mike

That's interesting. I think I had read about the C-clamp need on gnttype.org somewhere. Maybe when changing to bigger wheel cylinders and needing to bleed? So, this C-clamp method is recommended whenever you have to bleed the system?
This whole bench bleeding thing is a little confusing. The instructions that came with my 84 Regal hydroboost MC say never to push more than 1" when bench bleeding. My MC only came with port plugs so I tried bleeding it on the car with those. It seemed like only the rear reservoir bubbled consistently while the front didn't bubble much at all. Was I not pushing the brake pedal far enough? After reading this, I am not so sure I am ready to bleed the lines. I might bench bleed my MC on the car with port adapters and hoses in each reservoir. How far would the pedal need to be depressed if bench bleeding the MC on the car?

 

[Stroker-ace]

I bench bleed in a vise with a big phillips head screwdriver, the last one I did I pushed in and out for about an hour and 1/2. Be patient, no air bubbles AT ALL are allowed. Really push it hard till it bottoms out, slowly. The master cylinder should come with fittings and hoses to bench bleed. You will be surprised how long it takes before there is no air bubbles, usually there is 1 air bubble per push and this can go on for up to 400 to 500 pushes. Do not let the fluid go dry in the master cylinder or you will have to remove it and start over. Take the time and you will have the best brake pedal you have ever felt. Rebuilt is fine.
There is also a valve on the proportioning valve (on the front) that has to held in with a C-clamp, if it pops out you have to start over (do a search on this). MP brakes sells a part that screws into the prop. valve to eliminate the need to C-clamp the factory valve. You only need to change the prop. valve when you make a change like front disc and rear disc. If you still have front disc and rear drum you will be fine. If your valve is OEM and is 25yrs old, well, might be a good time to install a new one. MP brakes sells new ones. If you install a new prop. valve soak the fittings in WD-40 and use only super high quality line wrenches to loosen the fittings or you will be replacing all the brake lines as well. Don't rush it.
Disc Brake & Brake Conversion Kits, Suspension Kits: Master Power Brakes.
Mike

I cant seem to find that piece you are talking about to eliminate the factory valve. Can you post a link for me? thanks for all the info too!!!!

I was wondering what that little valve on the front of the prop valve was. it pops out every time I hit the brakes.