I think my proportioning valve....
 

has gone to the bad. When I first got the crew the brake warning light stayed on, so I unplugged it. It had good brakes, so a simple fix. I swapped the rear end for an 88 up 10 bolt to get a better gear for my ls swap. It hasnt really had good brakes since I started driving it again. I had It on the rack yesterday and noticed a fluid leak from the drivers rear wheel. I pulled the drum and the wheel cylinder was leaking. So new shoes and cylinders were in order. I cannot seem to get any pressure to the rear wheels. They will not bleed. I checked the rear line at the hose and I am just getting a dribble of fluid. I checked the master cylinder with a pressure gauge and I am getting 1200 psi with the truck running.

I did not run the master cylinder dry so the pressure differential valve should not have moved and the stem on the front of the valve will not move.

Any Ideas where to get a valve for our trucks? It's an 87 2500

Re: I think my proportioning valve....
 

Inline Tube & CPP both offer 'new' brass GM style replacement prop valves.

Before you buy one.... what is your process for bleeding? I ask because I've had similar issues on more than 1 truck. It was a frustration to say the least. The cure was I slightly changed by bleeding SOP (procedure).

Re: I think my proportioning valve....
 

Start at the right rear wheel and work to the left front. When I get some help here, I am going to bleed from the master to the valve, on both sides of it, then to the rear hose, then both wheels. Its just frustrating, I wanna ride in this thing and it ain't cooperating.

plus since it was rolling I took my bike apart and now have two apart in the shop. Oh well Que sera, sera Jay

Re: I think my proportioning valve....
 

When you're bleeding, are you starting w/pressure on the pedal, opening the bleeder valve until the pressure drops, closing the valve, & then removing pressure from the pedal?

Re: I think my proportioning valve....
 

Yes. I have plenty of bleeding practice. from mild repairs to brand new systems. But thanks for asking you just never know.
I just gotta bleed it from the master out and see where the pressure stops at. I just can't do it alone. Stop by if you get a minute:lol:

Jay

Re: I think my proportioning valve....
 

you may knocked the safety deal over in the prop valve. my 73 drove me nuts trying to bleed the brakes.. took the prop valve apart manually reset it and gravity bled finnaly got rear brakes

Re: I think my proportioning valve....
 

Not questioning your procedure, just verifying if it was the same as what I was doing.

What worked for me (on more than one truck)? I tried bleeding the brakes w/o the initial pedal pressure:
1) Brake pedal is @ rest
2) Open the bleeder valve @ wheel
3) W/the bleeder valve open, press the brake pedal slowly (intentionally slow)
4) Once the pedal is all the way down, close the bleeder & release the brake pedal

I tried the 'reset the prop valve' deal mentioned by 'KQQL IT' but was not sucessful. I then tried bleeding using the above method in an attempt @ something slightly different to see if I got different results & it did the trick. My best guess is the pedal pressure was not allowing the pin/plunger to move.

It's worth a shot if there's no sure solution.

Re: I think my proportioning valve....
 

Bled it at the valve, and then it bled on out and now has good pedal. Musta been some rouge air. Jay

Re: I think my proportioning valve....
 

Thats good to hear.