1988 Chevy Suburban no brake fluid getting to the wheel cyl

Tiny
MY SUBURBAN
  • MEMBER
  • 1988 CHEVROLET SUBURBAN
Brakes problem
1988 Chevy Suburban V8 Two Wheel Drive Automatic

the vehicle in question: 1988 Suburban, 454, 2WD, full floating rear end, front disc rear drum brakes, mileage is 30,000 ( rebuild of engine) actual miles unknown but over 100k.
I just replaced the rear bearings and seals then moved on to the brakes, the reason I took the rear axles apart in the first place, I replaced the shoes, wheel cylinders and the short brake line to the drivers wheel from the back of the rear end.
After I put the drums on I started to bleed the brakes. I now have no brake fluid getting to the wheel cylinders. I took the line off that goes into the valve on the rear end and when the brakes are applied no fluid comes out. I went to the master cylinder and, removed the lines, got fluid to squirt out when pumped. I found another valve box under the radiator. I was able to get fluid to come out of it on all of the lines. Went back to the rear and got no fluid, but now a soft pedal to the floor. I kept the master cylinder reservoirs full the whole time while following the general brake bleeding rules.
Short of ripping out all of the brake lines and replacing all the valves I don't know what to do. Is this bis expense the only way to go or am I missing something in my work? Could you tell me how I should have done my brake work from start to finish for this vehicle?
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Wednesday, June 25th, 2008 AT 8:00 PM

6 Replies

Tiny
MASTERTECHTIM
  • MEMBER
1988 correct? Is the red brake light on the dash illuminated? If so then you probably tripped the pporportioning valve and we have to unstick it.
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Wednesday, June 25th, 2008 AT 8:05 PM
Tiny
MY SUBURBAN
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Tim,
yes, the light is on.
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Wednesday, June 25th, 2008 AT 8:24 PM
Tiny
MASTERTECHTIM
  • MEMBER
That means the porportioning valve is stuck. One way to get around it is to vacuum bleed the system to get fluid through it and equalize the pressure on both sides of valve so it will unstick. This is very common and happens alot. 99 percent of the time you dont have to replace any parts just bleeding it. Sometimes its just a lucky push of the pedal that opens it or sometimes I take them for a careful ride and eventually brake fluid gets past it enough so it can be bled, but vacuum bleeding is the most successful.
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Wednesday, June 25th, 2008 AT 8:32 PM
Tiny
MASTERTECHTIM
  • MEMBER
Also when bleeding, use slow steady presses of the pedal not fast jerking ones, that will just make air bubbles in the line
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Wednesday, June 25th, 2008 AT 8:33 PM
Tiny
MY SUBURBAN
  • MEMBER
Tim,
So. For the not so smart (and my fancy worthless Chilton's) that don't know how to vacuum bleed the system can you give some directions?
John.
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Wednesday, June 25th, 2008 AT 9:12 PM
Tiny
MASTERTECHTIM
  • MEMBER
You will have to either borrow one from the parts store or purchase one. It basically attaches to the bleeder screw and it has a pump that is either hand operated or air compressor powered, and when you apply vacuum to the bleeder it will suck brake fluid past the porportioning valve to the bleeder and once the air is out it makes it easier for the valve to reset.
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Friday, June 27th, 2008 AT 5:18 PM

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