I am new to this drum brake stuff so bear with me.

I was trouble shooting some issues I have been having with my trucks and was going to start with adjusting my rear brakes. I opened up the fluid reservoir and found a major problem. The fluid level in the front compartment was darn near dry. I am guessing this is a majority of my brakes locking up and parking brake not holding.

So the big question is how do you properly bleed the brake system in these trucks? I have not dealt with many drum brake setups and want to make sure I do this correct the first time.

 

Losing brake fluid in any amount is not strictly speaking, EVER a good thing. Do you know where the brake fluid went? I think I'd be looking to determine the leak location first.

But in any case, there's about a dozen good write-ups about brakes in the sticky.

 

If you've got anti-lock rear brakes the first bleed is the anti lock valve on the frame rail in the rear. Then you bleed wheel cylinders longest line first then shortest. After they are done calipers the same way longest first.

As far as the MC being low and poor e-brake performance I would suspect either a leaking wheel cylinder - which might be seen on the rear drums - or well worn brake shoes. It could also be caused by your rear brakes being out of adjustment.

Bob

 

It sounds like you have a list of things to fix .
As for bleeding , use something like a turkey baster to suck out old fluid , if slug at bottom stir up / brush & suck that out also , then fill reservoir , open all bleeders [ 4 wheels ] , let drain till fluid at bleeders is clear , but do not let res. go empty .
If you start out like you are [ empty ] then it may take some pumping to get started & maybe finished , to start , just very short strokes on peddle , maybe 1/4" , could take 3-15 strokes , then let flow .
In both cases , check peddle to see if there is any air in system , if so open 1 bleeder at a time , let drain for about a couple table spoons worth , check after each bleeder , to see which is the problem .
On older trucks cars , with no or simple ABS , you bleed almost anyway .
But on newer trucks , cars with more intensive ABS , the procedures can get complicated , we have found that just draining is the easiest & does all without looking up procedure .
The last thing may be , if the proportioning valve got tripped , once there is some pressure on peddle , close all bleeders , press hard on peddle , if there is enough air bled out and the peddle is hard enough , you need to press peddle hard till you hear/feel a pop , that would be the valve returning to normal position .
When

 

I am planning on bypassing the RWAL valve. I am also seriously considering upgrading the shoes and wheel cylinders while I am down there. After that I will go into bleeding the system.

Do you have break into the drum to bleed the rears?

Where is the bleed port on the rear drum brakes?

 

The bleeder should be on the outside of the backing plate .
If you hear asking these questions , than I would guess that you should not try to re engineer the braking system [ RWAL ] , but the upgrading of the R. wheel cylinders to the GM ones , I have read is a good option .