PDA

View Full Version : having a hard time with bleeding brakes, 72 blazer?anyone?


jnyblazer
06-15-2012, 10:23 AM
we started at the farthest like we are supposed to. still no luck? and having the same problem on my 86 blazer, no back brakes! do you have to hold out the proportioning valve or something?and no we didnt let the master cylinder run dry. worked befor, should work now....lol anyone want to come put some work in for beer and pizza or something

Leithmc
06-15-2012, 11:06 AM
What made you decide to bleed them? Did you blow a line or wheel cylinder? The proportioning valve may have dropped back to pprevent fluid loss. Stomp on the brake pedal hard, and see if it resets.

jnyblazer
06-15-2012, 11:08 AM
we changed the line front and bck for the lift it moves in and out is that right?

Leithmc
06-15-2012, 11:22 AM
What moves in and out? The proportioing valve has a piston internally. You won't see it move. You will feel it reset itself generally when you stomp on the pedal. kind of a thump in the pedal. The problem is that you have no fluid to the back. Correct? If you've changed out all the lines, you'll have to pump it through by depressing the pedal slowly over and over so as not to trip the valve. make sure you run a line from the bleeder into a bottle. you want to have enough fluid in the bottle so the hose can't suck air back through when you release the pedal. depress the pedal slowly, let it up, wait a couple seconds, repeat. Patience is a virtue here. A pressure bleeder is very handy in these cases.

Leithmc
06-15-2012, 11:25 AM
Or you may have a bad master....

jnyblazer
06-15-2012, 11:33 AM
so you cant get someone to push down and hold, open the bleeder till it stops and close it? and we have a pressure bleeder? it seems to work but still get no brakes, and we are thinking of changing the m/c how do you bench bleed?

Leithmc
06-15-2012, 11:37 AM
The bench bleed is really pretty easy. I'd say google it (youtube) Way easier than explaining with words.

Apathy
06-15-2012, 11:42 AM
Are your rear drums adjusted properly? Blead all you want and the pedal will still go to the floor

jnyblazer
06-15-2012, 11:48 AM
The bench bleed is really pretty easy. I'd say google it (youtube) Way easier than explaining with words.


thx, going to try.and to adjust you go from the backing plate and with a screw driver turn out the adjuster till it hits the drum? and then stop?

Apathy
06-15-2012, 12:11 PM
Pretty much. Or you can measure with a large caliper

4skin
06-15-2012, 02:03 PM
i find opening the bleeders and leting it gravity bleed
before doing the pump and crack bleeders works best
and dont pump pedal fast slow and steady

Happypants
06-15-2012, 04:32 PM
i find opening the bleeders and leting it gravity bleed
before doing the pump and crack bleeders works best
and dont pump pedal fast slow and steady

X2

godtool
06-15-2012, 08:34 PM
I had same problem on 83 Chev. Still no rear brakes. Was told to stomp hard or open front bleeder on a calliper then stomp hard to reset valve. Still no time to try that. I let my rear brakes gravity bleed. Still I'll try what Leith said when I got time lol. I tried taking proportioning valve apart where wire goes on yet cant get a wrench to fit. I have extra proportioning valves and was just going to try a re&re and then gravity bleed before manual bleeding with an assistant.

Trailjunkie
06-15-2012, 08:38 PM
i find opening the bleeders and leting it gravity bleed
before doing the pump and crack bleeders works best
and dont pump pedal fast slow and steady

[stupid][stupid]

85chevy
06-15-2012, 08:42 PM
What is probably causing ur problem is the Pressure Differential Valve which when u have equal pressure stays centered but if u lose pressure on one side it will shuttle over and not let u bleed the brakes properly

jnyblazer
06-15-2012, 10:58 PM
both trucks needed back brakes, lol silly us lol oh well happy to find it, . not my truck so just do what mike puts on the table. thing was a death trap.

thanks everyone[cheers] we will bleed them tomorrow. for the last time..lol

jnyblazer
06-16-2012, 10:23 PM
Are your rear drums adjusted properly? Blead all you want and the pedal will still go to the floor

thx apathy...sometimes it just something simple....