Brake question /pls help

[slugish]

not getting any brake fluid to rear brakes when trying to bleed them after new wheel cylinder

* removed brake line fitting halfway up frame > pumped brakes --no fluid

* removed brake line fitting from master cylinder > brake fluid spurted everywhere<

* Question: what is the electrical line running to the distribution box (single prong connecter) supposed to do . ??

[mopar346]

Connector is for the brake light switch.

Many times when you replace lines or components in your brake system you have to work to get the fluid to the component again. I have used vacuum pumps, gravity and taking the line completely loose and having someone slowly push the pedal down and use my figure as a one wa check valve. As aggravating at it can be it always come through in the end.

The metering block or proportioning valve has a slider valve in it that is designed to flip to one side in the case that you completely loose fluid resistence in one end or the other, effectively sealing that end and allow you to have brakes on the other end (a safety regulation I think). I have heard of cases where it slides to one end and sticks effectively shutting off flow to one end. Again, I have heard of it but never had it happen to me.

Good probability that if you get a friend and keep working at it you will get fluid eventually, but it can be a pain. Vacuum or pressure bleeding works the best.

Good luck.

[slugish]

Originally Posted by mopar346

Connector is for the brake light switch.
Thx Mopar 346,

you have been very good at responding to my dilemmas.

As far as pressure bleeding , do you mean taking an air hose & trying to blow thru .& using a vacuum to try to draw the fluid thru?
Many times when you replace lines or components in your brake system you have to work to get the fluid to the component again. I have used vacuum pumps, gravity and taking the line completely loose and having someone slowly push the pedal down and use my figure as a one wa check valve. As aggravating at it can be it always come through in the end.

The metering block or proportioning valve has a slider valve in it that is designed to flip to one side in the case that you completely loose fluid resistence in one end or the other, effectively sealing that end and allow you to have brakes on the other end (a safety regulation I think). I have heard of cases where it slides to one end and sticks effectively shutting off flow to one end. Again, I have heard of it but never had it happen to me.

Good probability that if you get a friend and keep working at it you will get fluid eventually, but it can be a pain. Vacuum or pressure bleeding works the best.

Good luck.

do you mean use an air compressor to push the fluid thru or use a vacuum to suck it thru ?

Thx for your responses . You have been very helpful to all my distress posts.

[UPNADM]

Try gravity bleeding it... Fill your reservoir, then open your bleeder screws at the rear... Walk away and come back after 15 or 20. You should have fluid dripping from your bleeder screws. Then manually bleed the system, aka, get someone in and pump the brakes, hold the pressure while you open the bleeder screws.

You likely know this, but start at the passenger rear wheel.

[V30 mongo]

Sound like that little proportion valve is stuck. If you are lucky, you might be able to push the rod inside the valve by releasing pressure on the other side of the valve (open the bleaders on the front brakes and leave them open) then apply pressure to the back brakes. This might force the rod inside the proportion valve to center. Be careful as you could push the rod inside the valve all the way to the other side and block off the front brakes. If all fails the proportion valve is not hard to change. On C/K-R/V trucks it is located on the rear of the front crossmember and held on with two bolts.

[geezer#99]

The normal way to bleed the brakes is to depress the little button in the front of the prop valve and keep it depressed until your done bleeding.
Pop the rubber cap off the front to find it. You have to keep it depressed until you're done.

[mopar346]

Originally Posted by slugish

do you mean use an air compressor to push the fluid thru or use a vacuum to suck it thru ?

Thx for your responses . You have been very helpful to all my distress posts.

Kinda but not exactly. It is a tool that straps onto the master cylinder and you hook air to. The pressure is regulated down to a few pounds and whenyou open the bleeder it pushes the fluid through the lines.

In every case make sure you keep enough fluid in the master not to run dry and pump air into the system or you have to start all over.

[mopar346]

Originally Posted by geezer#99

The normal way to bleed the brakes is to depress the little button in the front of the prop valve and keep it depressed until your done bleeding.
Pop the rubber cap off the front to find it. You have to keep it depressed until you're done.

Interesting in 30 years in the car business and a lifetime of playing with cars I have never heard this. Any additional info or pictures?

[geezer#99]

Check here! post #9. Mentions it. It's in the assembly manual. I'll keep looking for a pic.
I'm the same as you. Never heard of it till recently.
http://67-72chevytrucks.com/vboard/s...leeding+brakes

[slugish]

Originally Posted by geezer#99

Check here! post #9. Mentions it. It's in the assembly manual. I'll keep looking for a pic.
I'm the same as you. Never heard of it till recently.
http://67-72chevytrucks.com/vboard/s...leeding+brakes

The post from the link you gave was for the 67-72 trucks .

Do the 81-87,s have this button you supposed to depress while bleeding .

I didnt see one on my 84 ( Iwill look again however)

Iwill try loosning. the bleeder screws on the front > dpress the pedal & see what happens as one of the posts suggested .

Thx to all Will

[mopar346]

Have someone who can close the bleeders before you take pressure off the pedal or you will suck in air and have a worse issue.

[mopar346]

Originally Posted by geezer#99

Check here! post #9. Mentions it. It's in the assembly manual. I'll keep looking for a pic.
I'm the same as you. Never heard of it till recently.
http://67-72chevytrucks.com/vboard/s...leeding+brakes

That thread had some misinformation and even the OP said in the last post the valve didn't need to be closed when bleeding, I take that to mean the button didn't need to be pressed. INteresting statement though I might keep it in mind if I ever have trouble with what must would call the normal way.

[geezer#99]

THe link I gave was for info only with pics of the boot and plunger. THere's always some mis-information in every thread. Just like in this one.
I have a 1976 repair manual and a 1984 repair manual and they both show the cap and plunger and a description of what it's for. Not all prop valves have it but most do.
Just cause it came from 67-72 doesn't mean it doesn't apply to your situation.

[slugish]

Yea mine has the rubber button on it that you can depress.

Going out & 1ST SEE IF I can get any fluid out of my front brakes

If I can ,I guess the rear brake side of the proportioner isnt moving where it shooud & restricting flow.

So then Iwill take the proportioner off & then whatcan I do with it -beat on it or what . Iassume it will have to be replaced ?

If so where could I get one .

So if Ican get my front brakes to bleed , no need to clamp that button --right ? If I cant Iwill try & clamp it .

Iknow its best for 2 people to do this but its just me for now > Ihave bought one of those 1 man bleeder bottle with hose from advance .

Ill keep yall posted

[slugish]

front brakes bled fine
tried rear brakes again --nothing-
clamped the button on the proportionor & tried again > nothing
removed proportioner (PITA) old fittings all got rounded off trying to remove
vice grips to the rescue
will try to find another proportioner > any ideas ?

[KQQL IT]

My 73 did the same. Had to manually reset prop valve and gravity bleed. Best brakes of the fleet now.
Posted via Mobile Device
Had to pull rear brake line from valve and push it in with a small screwdriver

[slugish]

Originally Posted by KQQL IT

My 73 did the same. Had to manually reset prop valve and gravity bleed. Best brakes of the fleet now.
Posted via Mobile Device
Had to pull rear brake line from valve and push it in with a small screwdriver

How did you manually reset prop valve ?

what did you push in with screwdriver in rear brake line . ?

[slugish]

Originally Posted by slugish

How did you manually reset prop valve ?

what did you push in with screwdriver in rear brake line . ?

Also gravity bleed ??

[KQQL IT]

Take the brake line off going to rear brakes. And jam a screw driver in that port you can feel the safety check valve go back.

Gravity bleed: open bleeder fill resivor(sp) full and keep full gravity will pull the fluid down to bleeders its slow but works well.
Posted via Mobile Device

[KQQL IT]

the pressure differential valve need to be centered or you will never get the rears to bleed. or you have massive air in the system...
Posted via Mobile Device

[krazy_texan]

I have a garden sprayer filled with brake fluid and a little plastic tip on the end of the line that I use. I disconnect the line from the master cylinder and open the rear bleeders, put my hose in the line and fill it. Have a buddy close the bleeder screws. Reconnect the lines to the master cylinder and bleed like normal. This works every time without a hitch and saves your right leg from a ton of pumping.
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[slugish]

Originally Posted by KQQL IT

Take the brake line off going to rear brakes. And jam a screw driver in that port you can feel the safety check valve go back.

Gravity bleed: open bleeder fill resivor(sp) full and keep full gravity will pull the fluid down to bleeders its slow but works well.
Posted via Mobile Device

Thx Kool it .took the proportioner all the way off last night .

will try pushing the valve in with screwdriver like you suggested . Hope it works cause those things are expensive if you can find them . wonder since Ihave the valve all the way off ,if Ican put some kind of lubricant in it to prevent it from sticking in the future

[KQQL IT]

Now that you have air in the whole system. Be very carefull and patient bleeding your brakes
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[slugish]

just ordered a prop. valve from summitt > cant beleive they had them > for 45.00 > exact same one as another supplier had for 78.00 . brothers also has a universal one that is mainly for the rear disc conversion .

tried to get the slider valve to move like Kool it suggested , but couldnt .

will get the new one on next week & let yall know the outcome .

I ask for so much help on here without really being able to give any worthwhile advice , I hope this helps with those that encounter the same problem Ihave .