Diagnose brake bleeding issue on 82 k20

[jordanmilne123]

Its been hell trying to get these rear brakes working. Who ever owned the truck before me never used the rear brakes. Fronts work great, but the parking brake didnt work because someone adjusted it to max trying to fix the underlying hydraulic issue. I replaced the shoes and wheel cylinders, 1 brake line and the rear brake hose, so i know there are no issues there. The parking brake works and is adjusted. I cant get the brakes to gravity bleed without issue, but for some reason I cannot build up pressure. Front calipers are great, but wheel cylinders do not squirt when bled like they should. I looked into the proportioning valve issue, but i believe mine is fine as when I depress the brake pedal the pin pops out. One thing I have realized is that when I depress the brake with the top off the reservoir, the fluid level of the front brakes stays the same, but the rear fluid level rises almost like there is a little spring in the fluid. I'm starting to think I have a bad master cylinder or a big air bubble in it or something. Any Ideas on this one? I'd like to see if i cant figure is out before i start dumping money into it without knowing.. THanks guys!

 

[jordanmilne123]

I also have realized that it appears that I have the master cylinder for the 11" rear brakes installed on my truck even though my truck has 13" brakes.... could this be causing the rear brake issue??

 

[chengny]

Couple of things:

First do you mean that you can get the rear wheel cylinders to gravity bleed when you say this?:

I cant get the brakes to gravity bleed without issue, but for some reason I cannot build up pressure.


Second:

Do you have a "HEIGHT SENSING BRAKE PROPORTIONING VALVE" in the rear brake hydraulic circuit?

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