Unable to bleed rear brakes

[84 Shorty]

I recently changed out the hard lines on my rear axle and the soft flexible hose. I tried bleeding the brakes and no fluid comes out either side from the bleeder valve. My wife was hitting the pedal and it barely squirts out of the valve and pedal didn’t even budge.

I even tried pulling both valves and letting it gravity bleed, still nothing. I pulled out both hard lines that screw into the flex line and had hit the brake pedal. It would barely squirt out both sides, is this normal? Something wrong with the proportioning valve?

 

[chengny]

I recently changed out the hard lines on my rear axle and the soft flexible hose. I tried bleeding the brakes and no fluid comes out either side from the bleeder valve. My wife was hitting the pedal and it barely squirts out of the valve and pedal didn’t even budge.

I even tried pulling both valves and letting it gravity bleed, still nothing. I pulled out both hard lines that screw into the flex line and had hit the brake pedal. It would barely squirt out both sides, is this normal? Something wrong with the proportioning valve?

It would barely squirt out both sides, is this normal? Something wrong with the proportioning valve?

Short answers: No and possibly yes.

Each time the brake pedal is depressed - with the brake lines disconnected - a large volume of brake fluid should be discharged from the open lines.

As to the reason why you are not getting that volume to flow out, it could be due to a number of possible issues:

1. A problem with the master cylinder. Loosen - but don't disconnect - the line to the BPCV at the MC and check for flow out of the MC.

2. The spool within the BPC valve may be partially shifted over and is not allowing full flow to the rear circuit. Normally this would be indicated by the brake warning light on the dash. Does the warning light work - say when the e-brake is engaged? Try pulling the lead off the BPC valve and grounding it to the frame - it should cause the warning light to illuminate.

3. It may be as simple as a restriction in the rear circuit's common supply tube. You might want to try disconnecting the common rear circuit line at the BPCV and checking for flow there. If that is good suspect the common line. If there is good flow into the BPCV - but only a trickle out of it - try centering the spool. That procedure is explained in many threads here.

To diagnose this problem will not be rocket science, but it will require a methodical procedure that involves opening the system at various points and determining where the flow restriction is located.

 

[Rusty Nail]

I bet the rear brakes are assembled wrong OR broken springs/some **** is to blame. Maybe the adjusters are frozen or rusted.
BET!
Bettin the brakes do NOT acuate completely as a result and this results in your weak fluid flow.

If not, listen to @chengny !

 

[HotRodPC]

Just for ***** and giggles. Give this a try. With the rear bleeders snugged up. Bleed the Right front (Passenger Side), then the Left front (Driver Side). Then, start at the back again, Right Rear (Passenger Side), Left Rear. If it seems to have went well doing the rears, then go ahead and finish off and do the right front again and then the left front again. Hopefully it'll work.

I have seen this work a time or two.

 

[Rusty Nail]

You got no faith in an underlying mechanical problem?

Is this a FullFloat rear by chance?

 

[hatzie]

Sounds like the warning lamp switch piston in the combination valve is shifted to block the rear brakes. Open the front bleeders and press the brake pedal til the BRAKE lamp goes out.

You must be registered for see images attach

There is a plastic tool to lock the warning lamp switch piston once it's centered. When the switch piston is centered you temporarily replace the warning lamp switch with the tool to lock the shuttle in place so it doesn't shift to close the forward or rear fluid circuits while you're bleeding the brakes.
Open the front bleeders and press the brake pedal til the BRAKE lamp goes out then replace the switch with the tool.

https://www.summitracing.com/parts/...LUlZ5EZqCq4MfmyA75INBC4ssPgkS3BsaAp_UEALw_wcB

You must be registered for see images attach

There are also tools to open or lock closed the metering valve to the front brakes but I've never needed one.

You must be registered for see images attach

You must be registered for see images attach

 

[Jerry phillion]

I know you replaced the rubber hose in rear. I had a similar
Problem and my rubber hose was collapsed.i would ck to see if you have good pressure at hose outlet.then ck pressure from hard line
At hose inlet. This will help indicate where problem is.i learned
To blow thru every pc of brake line before installing.

 

[84 Shorty]

Sounds like the warning lamp switch piston in the combination valve is shifted to block the rear brakes. Open the front bleeders and press the brake pedal til the BRAKE lamp goes out.

You must be registered for see images attach

There is a plastic tool to lock the warning lamp switch piston once it's centered. When the switch piston is centered you temporarily replace the warning lamp switch with the tool to lock the shuttle in place so it doesn't shift to close the forward or rear fluid circuits while you're bleeding the brakes.
Open the front bleeders and press the brake pedal til the BRAKE lamp goes out then replace the switch with the tool.

https://www.summitracing.com/parts/...LUlZ5EZqCq4MfmyA75INBC4ssPgkS3BsaAp_UEALw_wcB

You must be registered for see images attach

There are also tools to open or lock closed the metering valve to the front brakes but I've never needed one.

You must be registered for see images attach

You must be registered for see images attach

The connection for the warning lamp is gone. I removed the rubber boot on the proportioning valve and the stem is definitely sticking out. Do you think I could just C clamp the end to prevent it from moving in and out till I get the shuttle centered?

 

[84 Shorty]

You got no faith in an underlying mechanical problem?

Is this a FullFloat rear by chance?

Nah semi float

 

[hatzie]

The connection for the warning lamp is gone. I removed the rubber boot on the proportioning valve and the stem is definitely sticking out. Do you think I could just C clamp the end to prevent it from moving in and out till I get the shuttle centered?

The J23709 tool can be fabbed with a drill and a vise.

 

[HotRodPC]

I know you replaced the rubber hose in rear. I had a similar
Problem and my rubber hose was collapsed.i would ck to see if you have good pressure at hose outlet.then ck pressure from hard line
At hose inlet. This will help indicate where problem is.i learned
To blow thru every pc of brake line before installing.

Normally or at least when I've seen collapsed hoses, they'll let fluid through, but won't let it back up so the brakes stay applied. He's having problems getting fluid THROUGH to the bleeders.
So are you saying yours collapsed and did not fluid go through?

 

[HotRodPC]

Sounds like the warning lamp switch piston in the combination valve is shifted to block the rear brakes. Open the front bleeders and press the brake pedal til the BRAKE lamp goes out.

You must be registered for see images attach

There is a plastic tool to lock the warning lamp switch piston once it's centered. When the switch piston is centered you temporarily replace the warning lamp switch with the tool to lock the shuttle in place so it doesn't shift to close the forward or rear fluid circuits while you're bleeding the brakes.
Open the front bleeders and press the brake pedal til the BRAKE lamp goes out then replace the switch with the tool.

https://www.summitracing.com/parts/...LUlZ5EZqCq4MfmyA75INBC4ssPgkS3BsaAp_UEALw_wcB

You must be registered for see images attach

There are also tools to open or lock closed the metering valve to the front brakes but I've never needed one.

You must be registered for see images attach

You must be registered for see images attach

This is what I'm what I'm thinking too and why I suggested for ***** and giggles to bleed the front right, then left front. After that, then go to the right rear and see what he's got. I was told before, I tried it, and it did work. The valve can get hung up and not move or when it did move, it didn't come all the way back home where it belonged and proportions were off and wrong. So what I was told, by bleeding the front brakes first in this case, IT SHOULD cause the valve to swing all the way one way, then bleed the other side and cause the valve to swing all the way back the other way. Then when you pump them back up, it should reset the valve to where it's supposed to be. It did work for me. Now this does not mean that the valve can't be defective or have developed a rust spot to where it can't move or make full swings like it should when you bleed. In that case, it's not going to work.

 

[HotRodPC]

Give us an update @84 Shorty . Notice I got this ID changed. If you want me to update the email addy on this account, I can do that too. Just send me a PM and let me know.

 

[Jerry phillion]

Hot rod--- I had this same problem with my sons 67.
Took one rear brake line off, pumped pedal, no fluid.
Did Same for other side, still no fluid. Pulled off rubber
Hose and tried to blow thru it. Plugged up or collapsed.
Lightly pushed on brake pedal and fluid was right there.
Replaced rubber hose , bled brakes as normal. Had
Great brakes. Now whenever I replace brake lines, I
Blow thru to make sure they are clear.

 

[84 Shorty]

I did what some of you suggested. I opened up both front bleeders and mashed the **** out of the pedal a bunch. I’m guessing the shuttle centered up because I got pressure out back. Finished bleeding everything and now it’s good to go. I had no idea about the proportioning valve, damn these older vehicles...