Rear brake bleeding struggles

[Chris64]

74 k20. I'm new to these things aside from dirt bikes and quads.

I don't know if the rear brakes were working before but the pedal was mushy. I bled the front brakes fine (ish).

When I went to bleed the rear left the vacuum wasn't pulling any fluid at all. The bleeder screw was cleaned out before trying. So I tried the old pedal pump method and that seemed to work.

I was afraid I messed up the proportioning valve but I'm assuming that this was not the case if the rear left was working.

It still seems odd that it worked pumping but not vacuuming. No biggie. Got a few bubbles out and topped off the reservoir.

On to the right side rear. Cleaned out the bleeder screw (brake cleaner, small wire). Note: neither side leaked fluid with the bleeder screw removed. Maybe that's normal for rear brakes.

The vacuum wasn't pulling anything so I tried the pedal and nothing was going to that drum at all from the pedal.

I have the proportioning valve that has the little reset button for the front (I believe).

Any thoughts of how I should diagnose this? It almost seems like that line from the split on the axle is clogged because I could pump fluid through the rear left. That said the brakes on the rear are not working at all.

Also when pumping the brakes we do this with the motor off. I'm assuming that's correct.

 

[Normmus]

Maybe the rubber part of the line is collapsing when applying the vacuum, and a seized right rear wheel cylinder?

 

[Chris64]

Maybe the rubber part of the line is collapsing when applying the vacuum, and a seized right rear wheel cylinder?

That would explain the vacuum failure.

If it was seized, wouldn't brake fluid still come out of the bleed screw?

Bleeding brakes is something I've failed at with motorcycles/quads/mountain bikes and now trucks . The nice thing with this truck is I really don't even have to remove the tire to bleed it. It's pretty easy to access from the back.

 

[Grit dog]

If you had to clean out the bleeder screw, and no fluid came out of them, the wheel cylinders are shot.
Good news is , if the bleeders came out, you should be able to get the brake lines loose without much issue.

 

[Normmus]

yes it should, but the steel line could be blocked between the flex hose and wheel cylinder

 

[Rusty Nail]

Im goin with wheel cylinder too.
Also.
As well as
In addition to

They got that deal in the valve what goes to one side if it's bad so the rest still works?

Here's your clue, Blue.

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Gravity bleeding can't not work...
Somethin ain't right.

*edit"
Pintle! That's what that slidey deal is called.

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[Jimmyperf400]

Have you tried this yet get a friend or family member have them sit in the drivers seat open up one bleeder on either right or left your choice open up the bleeder and have who ever slowly push the pedal down with the pedal down close the bleeder then have them let the pedal up then do the same procedure until there is fluid from that side wheel cylinder if you get fluid close the bleeder then do the same on the other side. If you get fluid from both sides fill up the master open up both bleeders and see if fluid gravity bleeds from both sides. If so cap the master and bleed all of them one last time to remove any left over air. If only one side has fluid than there is a problem from the tee at the rear to that wheel. If neither of the rear gravity bleeds than there's a problem with the master. Hope this helps

 

[Chris64]

Have you tried this yet get a friend or family member have them sit in the drivers seat open up one bleeder on either right or left your choice open up the bleeder and have who ever slowly push the pedal down with the pedal down close the bleeder then have them let the pedal up then do the same procedure until there is fluid from that side wheel cylinder if you get fluid close the bleeder then do the same on the other side. If you get fluid from both sides fill up the master open up both bleeders and see if fluid gravity bleeds from both sides. If so cap the master and bleed all of them one last time to remove any left over air. If only one side has fluid than there is a problem from the tee at the rear to that wheel. If neither of the rear gravity bleeds than there's a problem with the master. Hope this helps

We did do this. The rear left bled fine. The rear right did not.

It seems like the line or the caliper is blocking any fluid from coming out. I guess I should pull the line out of the caliper and see if the fluid can get that far.

 

[Grit dog]

We did do this. The rear left bled fine. The rear right did not.

It seems like the line or the caliper is blocking any fluid from coming out. I guess I should pull the line out of the caliper and see if the fluid can get that far.

Confused, you have disk brakes in the rear on that truck? Or did you mean wheel cylinder?
You haven’t expounded on the basic condition or believed age of the brake components, but my assumptions was they are OLD. If that’s the case, any/all could be an issue and any/all components could/should be replaced.