brakes locking up

Rosco · 08-01-2012, 11:22 PM

Ok, I just got this truck and here we are

Im driving along, each time I hit the brakes the pedal gets tighter and tighter until the pedle is rock solid. At this point im pulled over because it feels like im driving with my brakes on

.. The brake pedal is rock solid, I can smell the brakes burning, and the brakes stay engaged so tight the car wont move. WTH

PLEASE HELP anybody have some insight!?!?!?!?!?!?!?!? by the way, after waiting a while the brakes release and everything seems ok until of course I drive again for a short distance... THANKS IN ADVANCE

08Canyon · 08-02-2012, 12:11 AM

Is the parking brake applied? If definitely sound as if the shoes are hanging up. It could be a bad adjuster at one of the rear wheels. I don't know if they can be installed in reverse and tighten too much but it seems like something is making them hang up.

Have you been able to isolate it from the front or the back? If it's the front, it's the caliper hanging up. You might want to try removing the drums and take a look at the system. The drum won't just lip off, especially if it's tight. You'll have to back it off using the adjuster. If you don't know how to do that, either look it up online or take it to a shop. I'm not sure how to explain it.

I am going to assume that no work has been done recently?

BlueBanditZ71 · 08-02-2012, 12:29 AM

Sounds like a possible probley with one of the following:Brake booster,Brake booster check valve,Brake pedel pushrod,Vacuum supply issues,Vacuum leaks.

Rosco · 08-03-2012, 04:20 PM

The stealership is telling me there is a valve in the master cylinder hanging up.... They want $680!!!! LOL I will pick up a referbished master cylinder from the parts store in the morning for $70! Hope they are right, definately makes sence. Thanks guys.

The Godfather · 08-03-2012, 04:29 PM

Quote:

Originally Posted by Rosco

The stealership is telling me there is a valve in the master cylinder hanging up.... They want $680!!!! LOL I will pick up a referbished master cylinder from the parts store in the morning for $70! Hope they are right, definately makes sence. Thanks guys.

can you keep us posted on the master cylinder swap? This sounds more like BlueBandit stated brake booster issue not a master cylinder issue. Of course these trucks are unique in some ways, good luck.

Rosco · 08-03-2012, 06:08 PM

Yeah, I will update when I get the master cylinder installed... I keep hearing all kinds of different things... I have had a couple people bring up the booster thought. So i'll start with the master cylinder, and hope for the best. If thats not it looks like i'll be researching the booster further...

The Godfather · 08-03-2012, 07:24 PM

Quote:

Originally Posted by Rosco

Yeah, I will update when I get the master cylinder installed... I keep hearing all kinds of different things... I have had a couple people bring up the booster thought. So i'll start with the master cylinder, and hope for the best. If thats not it looks like i'll be researching the booster further...

I hear you man. We help as best as we can with the knowledge and experience we've gone thru but nothing is set on concrete. The MC is less costly and less effort to deal with so yeah try that who knows. From my past experiences a sinking pedal has been a MC and a stiff pedal has been a booster. Good luck and make sure your system is properly bled after the replacement.

08Canyon · 08-03-2012, 08:06 PM

Make sure you bench bleed the master cylinder per the instructions. I know master cylinder seals fail and the pedal goes to the floor but I've never head of it in how you described it. Not saying it's not that, just saying I've never head that before.

Good luck!

Reeman · 08-04-2012, 12:29 AM

Quote:

Originally Posted by Rosco

Ok, I just got this truck and here we are

Im driving along, each time I hit the brakes the pedal gets tighter and tighter until the pedle is rock solid. At this point im pulled over because it feels like im driving with my brakes on

.. The brake pedal is rock solid, I can smell the brakes burning, and the brakes stay engaged so tight the car wont move. WTH

PLEASE HELP anybody have some insight!?!?!?!?!?!?!?!? by the way, after waiting a while the brakes release and everything seems ok until of course I drive again for a short distance... THANKS IN ADVANCE

Did you try ruling out the booster by disconnecting the vacuum hose to the booster. If it is the booster sticking this should allow non boosted use of the system. Your check break/abs light should indicate trouble with the vacuum disconnected. It is not legal to manufacture a vacuum assisted brake that will not work as a straight hydraulic when the boost fails.... so even though you will require considerably more pedal pressure to work the breaks they will still work even without a boost assist.

From your other post it sounds like the stealer is replacing the entire booster/master not just the master after the booster so it could be that you will need a new booster or at least one with a good diaphragm piston return assembly. It has been a few years but even today power breaks are not that complicated and at one time you could even rebuild boosters yourself....

I do not know what the rebuild kit situation is for newer GMCs brake systems now a days, but you would think that essential components that are as simple as a power break system would be easily rebuilt!

n9cv · 08-04-2012, 02:04 AM

When you replace the master cylinder, look closely to see if the master cylinder was leaking fluid into the booster.

08-01-2012, 11:22 PM	#1 (permalink)
Rosco Member Join Date: Jul 2012 Posts: 37	brakes locking up Ok, I just got this truck and here we are Im driving along, each time I hit the brakes the pedal gets tighter and tighter until the pedle is rock solid. At this point im pulled over because it feels like im driving with my brakes on .. The brake pedal is rock solid, I can smell the brakes burning, and the brakes stay engaged so tight the car wont move. WTH PLEASE HELP anybody have some insight!?!?!?!?!?!?!?!? by the way, after waiting a while the brakes release and everything seems ok until of course I drive again for a short distance... THANKS IN ADVANCE

08-02-2012, 12:29 AM	#3 (permalink)
BlueBanditZ71 Member Join Date: May 2012 Location: Taft Ca Posts: 70	Sounds like a possible probley with one of the following:Brake booster,Brake booster check valve,Brake pedel pushrod,Vacuum supply issues,Vacuum leaks. __________________ 07 Chevy Colorado Crew cab Z71 4x4 3.7L I5

08-04-2012, 02:04 AM	#10 (permalink)
n9cv Senior Member Join Date: Apr 2009 Location: Hebron, Indiana Posts: 1,571	When you replace the master cylinder, look closely to see if the master cylinder was leaking fluid into the booster. __________________ 2005 White 2wd Z71 WT

08-02-2012, 12:11 AM	#2 (permalink)
08Canyon Senior Member Join Date: Oct 2011 Posts: 3,057	Is the parking brake applied? If definitely sound as if the shoes are hanging up. It could be a bad adjuster at one of the rear wheels. I don't know if they can be installed in reverse and tighten too much but it seems like something is making them hang up. Have you been able to isolate it from the front or the back? If it's the front, it's the caliper hanging up. You might want to try removing the drums and take a look at the system. The drum won't just lip off, especially if it's tight. You'll have to back it off using the adjuster. If you don't know how to do that, either look it up online or take it to a shop. I'm not sure how to explain it. I am going to assume that no work has been done recently?

08-03-2012, 04:20 PM	#4 (permalink)
Rosco Member Join Date: Jul 2012 Posts: 37	The stealership is telling me there is a valve in the master cylinder hanging up.... They want $680!!!! LOL I will pick up a referbished master cylinder from the parts store in the morning for $70! Hope they are right, definately makes sence. Thanks guys.

08-03-2012, 06:08 PM	#6 (permalink)
Rosco Member Join Date: Jul 2012 Posts: 37	Yeah, I will update when I get the master cylinder installed... I keep hearing all kinds of different things... I have had a couple people bring up the booster thought. So i'll start with the master cylinder, and hope for the best. If thats not it looks like i'll be researching the booster further...

08-03-2012, 08:06 PM	#8 (permalink)
08Canyon Senior Member Join Date: Oct 2011 Posts: 3,057	Make sure you bench bleed the master cylinder per the instructions. I know master cylinder seals fail and the pedal goes to the floor but I've never head of it in how you described it. Not saying it's not that, just saying I've never head that before. Good luck!

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