Brake problems

[WadmalawJoe]

My brakes are hanging up. It just seems to be the back ones. I do not think emergency brakes are the culprit. Sometimes they seem fine, other times they don't release all the way. I took it to a garage thinking they could fix it faster/better.... They put on a new master cylinder and replaced the rear rubber hose and said they flushed the lines and all kinds of junk came out. It was fine when I picked it up and drove it home. Next day I run into town and back and the problems back or I guess never really left...
I'm thinking there is still junk in the lines and I need to flush them more.
Any other thoughts or suggestions?
One other thing, brake fluid, can it be the newer DOT 4 or 5? Shouldn't hurt anything??

Thanks!

[cdowns]

if there was alot of gunky junk in the fluid i'd worry about an excess buildup of it inside the brake cylinders causing a problem

[68gmsee]

You could try to flush more which is always a good thing t do, but I don't think that's going to solve the problems.

Can you give us more info... (Warning: lots of questions...)

-Do you have power brake booster?

-Did they do any other checks like the brake shoe lining for contamination or adjustment?

-Did they check the proportioning and/or distribution valves and check the wheel brake cylinders for binding?

-Do the brakes feel hot, drag or lock the rear tires?

-How long before they release so you can drive it again?

[WadmalawJoe]

Thanks and questions are no problem
No power booster

I doubt they checked proportion valve. How can I check it?

I checked and cleaned inside drums. Everything looked good and nothing seemed stuck. Also everything was fairly new.

Both back brakes get hot. They do not lock up. They don't really make any dragging noise that's extremely audible. There is only two ways I can tell, one I let off gas and truck slows down quick, get out and touch rims and they will be HOT. If I let it get hotter it stinks like hot brakes. I thought rear end but axle and gear box won't even be warm.

How long before release, I don't really know. I haven't driven it a lot. I just got the truck plus don't want to damage anything.
Posted via Mobile Device

[GMCJOE]

Sounds like your wheel cylinders are sticking. I would try replacing them, there pretty cheap. When you got it apart, pull your adjusters apart, clean them up and lube them up.

[68gmsee]

Start by making sure the brakes are adjusted properly. Raise the rear wheel and insure that it barely touches (drags) on the drum and maybe adjust one more click in on the adjuster.

One thing you can try while the wheel is off the ground. Chock the other three wheels and start the engine. Step on the brake a few times then quickly checked to see if the wheel is free. If it's dragging, try to remove the drum to see if you can find what is causing it to drag. If you can't remove the drum, loosen the bleed screw to see if it frees the brake. Let us know what you find.

Warning: if you do go with the brake cylinders, make sure the bleeder valve shuts off completely before replacing otherwise you will be wasting brake fluid and your time. Use a small hose and mouth suction or vacuum tester to check. I just went through this couple days ago.

[WadmalawJoe]

With non- power brakes the truck doesn't have to be running to function or does it? With power brakes you need the booster to work.
I did pick up cylinders, I happened to be at the auto store when gmcjoe posted and I got the email for it. Kind of odd that both would be sticky though.... we'll see...
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[68gmsee]

Originally Posted by WadmalawJoe

With non- power brakes the truck doesn't have to be running to function or does it? Posted via Mobile Device

No, don't have to be running. I had seen where you said no booster but forgot.

(Just to be sure: You mentioned they replaced a rubber line. Was it the one on the rear above the axle?)

As Cdowns mentioned, a buildup of nasty, contaminated brake fluid can cause cylinders to become gummy or rusted. If they haven't been replaced in a while it's good insurance. Be sure and check the bleeder valves to make sure they shut off completely when tightened before installing them. I wasted 2 hours and a can of fluid.

As I mentioned above the two main things that keep brakes from releasing properly are master cylinder and internally swollen and restricted rubber lines.
From there it could be restricted, bent or crimped hard lines (can be checked by ease of bleeding) maladjusted or contaminated brake shoes.

The distribution block may have a restriction and can be checked by loosening the rear brake line going to it.

[WadmalawJoe]

Thanks a lot ! I hope to get to this tomorrow. Thought I would today but with so many little projects to do on it I didn't get to them all.
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[midniteblues]

I had the same exact problem your describing on my pontiac turned out the e brake cables were hanging up.
they can play games with you be sure to completely rule them out

I've seen the rubber hose do the same too

If i were you I would do the wheel clys
and while they were disconnected ,disconnect that line from the master and blow it out then bleed them well

[WadmalawJoe]

Yeah!!!
I got it!
I replaced both rear wheel cylinders. Cleaned and lubed everything (didn't lube shoes of course). I even painted my drums. I have taken the truck for two test runs and brakes are fine. There was some rusty mud in the rear passenger side wheel cylinder. As soon as I disconnected the brake line it came oozing out. I also replaced the two lines back to the T-junction. The garage had replaced the rubber one. The brake lines I used I got straight stock ones from store for $3.99 and bent them myself. Both were about 4 inches to long so I had to get creative with my bending to use up the extra, otherwise I would've had to cut,re-flare etc etc.
I did the gravity bleeding method and it worked well. I was surprised how fast it actually went. I read that gravity bleeding takes about two hours. My master cylinder drained about a half inch every 5-6 minutes, so I had to stay on it to keep it from going dry.

[GMCJOE]

nice... glad to hear you issue is resolved.