1993 Sierra C1500 left front / right rear brakes stuck

[carlos2012]

I've been working on a 93 Sierra SL V6 1500 regular cab and found that the left front and right rear brakes are stuck. The truck has been sitting for a very long time, and I'm barely getting it running. I haven't checked the right rear wheel, but I have checked the left caliper, and it will release if I loosen the bleeder screw. How would one go about troubleshooting this issue?

 

[454cid]

...and it will release if I loosen the bleeder screw. How would one go about troubleshooting this issue?

The hose probably has internal damage and is acting like a check valve.

 

[carlos2012]

That's what I was figuring. Is there any information on the brake line circuits? Like does one circuit control the front, and the other the rear, or are they diagonal, left front and right rear?

 

[Donald Mitchell]

One for front and one for rear thru the combination/ proportioning valve.

 

[Erik the Awful]

If the other side works properly, your problem is after the tee on the differential.

 

[carlos2012]

That's what I'm figuring. I think the front left is fixed as it locks when the pedal is pressed, and releases when you release the brake pedal. Now, I have to turn my attention to the right rear brake. This would be my first time working with drum brakes on this kind of vehicle.

 

[Schurkey]

Wouldn't surprise me to find that the shoes have "rusted" to the drum. I had that happen on my truck, after it was parked for a few months.

Broke the lining on the shoe when I drove off.

 

[67GMC]

I'd have a good look under the truck. Trace the brake lines to make sure nothing broken and leaking if it's been sitting for a long time (especially on grass or farm field). My '88 was sitting out in a field for 3 years. Underneath, it looks like it was pulled off the Titanic. Every line rusted through (or close to). The flex lines were probably ok but as the hard lines were broken, the lines were fused into the flex lines.

Check the rear wheel cylinders too for leaks. If one drum is really dirty looking inside, chances are it's a leaking wheel cylinder. I agree with the others on the front brake. Probably flexline is bad if you can still move the caliper.

I have to say, the brakes on these trucks are overly complicated to do. Lines are easy to get and parts are cheap if you're thinking of a do-over.