Having an issue with a high brake pedal and dragging brakes. They act like I have my foot lightly on the brake pedal but I don't.
I backed off the adjusters on the rears which helped there but the last time I drove the truck on the freeway both front brakes were dragging and hot( smelling like burning brakes) when I got home.
I did a search and can't find an answer.
Some mention rubber brake hoses closing up, but mine seems to be happening on all four wheels at the same time.
Master cylinder?
Hydraulic brake booster? Is there a check valve on the Hydraulic systems?
*After looking through the repair manual it says possible "blocked master cylinder return port" or "faulty power booster(binds-does not release)"
Is the M/S return port integrated into the M/S body?

Anyone have this issue?

 

First of all, how many miles on the brakes, and when is the last time they were serviced?

FWIW, front brakes do get pretty hot in normal usage.

But if you're front brakes are hot and smelling like they're burning, you probably should take a look at them and see if the caliper(s) are stuck.

I haven't messed with drum brakes in a long time, but if you back off on the star adjusters, the pedal height should go down.

 

Thanks for the reply bulabula.
I think the front brakes were serviced around 15000mi ago.
A couple of months ago I did the GM wheel cylinder upgrade and had a good look at the rear shoes.
This past week in stop and go traffic I noticed that the brakes weren't fully releasing as I crept along and the pedal had almost no play in it.
I was thinking as the brakes warmed up, they were expanding and starting to drag on the rear, so I backed up the adjusters and got some play back in the pedal and all seemed good. Last night as I drove home it felt like the brakes were dragging again after I got off the freeway. When I got in my driveway, I could smell burning brakes and a lot of heat coming from both front rotors, but the rears were normal warm(probably because they're backed off so much)
Today I jacked up the front of the truck and the front wheels spin freely.
I have noticed that recently, the pedal height seems to change as I drive around. My guess is the brakes are hanging and releasing as I drive around.
Any input will be helpful and I have the day off tomorrow and will try to resolve this problem.

 

Going to try a new replacement brake master cylinder.
At this point it's my best guess as to what may be wrong.
Please speak up if you have any ideas.

Scott

 

On the front, make sure the calipers slide freely on the pins (bushing in the manual). I thought my caliper was bad & it only needed cleaning and lubeing.

 

Did you do the brake job or was is serviced somewhere?

Your calipers are probably sticking or the slides may be worn. Were all the pins, slides, and caliper lubed with anti seize brake lube?

 

I guess the sticking slide pins is a common problem but all four brakes were dragging.
I replaced the brake master cylinder and it seems to have cured the problem.
Someone mentioned that the master cylinder could become blocked internally if the brake fluid is dirty. Mine kind of looked like cola, and at the bottom of the M/C reservoir there was a brown colored sediment in there.
I was expecting to see a ridge in the bore of the M/C which the piston was hanging on, but didn't see one. I'm going to disassemble it tomorrow and post how much wear it find in it.

Thanks for all the replies and I'm keeping my fingers crossed that I found my problem.

 

Glad you found it!

 

Just an update to my Dragging Brake problem.
Replaced the brake master cylinder and all seems normal.
The brake fluid was dirty as heck and the bottom of the reservoir had a some brown silt and possibly drops of H2O.
Bled a 32oz bottle of brake fluid through the system until clear fluid flowed out.
I think this problem was occurring on and off for the last month or so because I would smell burning brakes once and a while,
look around for the idiot that left their parking brake engaged. I guess it was me!
I guess it does pay to flush you brake system.
Here's a few pics of the bottom of my reservoir, it's not a pretty sight.

 

H2 OH!
The water in the brakes gets hot and expands a bunch.
Which then causes the symtoms you described.

Be sure to keep the caliper pins well lubed.

SFB

 

No, I don't believe that the water in the system was the real cause of my problem. All four brakes were dragging at the same time, even before they had time to get very warm.
I believe the secondary piston in the brake master cylinder wasn't moving freely caused by the contaminated brake fluid.