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OK guys, I've searched the archives and haven't found this question asked. I've just installed a reman'd power booster and MC on my '69 (factory disc/drum) and now I can't get brake fluid to the rear wheels. I could before and I bench bled the MC. I've also read all my service manuals and found this passage:

NOTE: on cars with front disc brakes the spring loaded plunger the front of the proportioning valve must be depressed while bleeding. Wire or tape can be wrapped around the valve to hold the plunger in.

I can't find anything resembling a spring loaded plunger on my proportioning valve so I can't figure any way to comply with this part of the process. Has anyone else run across this? I saw some reference in the archives about having to reset the brake alarm indicator and my proportioning valve has an electrical connection, but I have no clue about how to reset this pressure valve.

I hope someone can help...Thanks,

 

[64Chevy2]

Hey pop,
I would do two things. Make sure the new booster rod to the master is adjusted properly and compare it to your old one if you still have it.
If you did'nt open the brake lines at the wheels, then you should not be having this issue, you already bled the master.
The other thing i would try is back bleeding. They sell a kit to do this, it's kinda of pricey, but napa has a sirynge for a couple of bucks.
You basically fill up the sirynge with brake fluid, remove the air from the sirynge all the way up to the hose, open the right rear brake bleeder screw and squeeze the brake fluid in, pushing the air up back up to the master cylinder. Good luck.

As far as the proportioning valve goes, if I remember correctly, might specify in the manual, you only have to do that if your using a pressure bleeder. You don't have to do that when your manually bleeding the brakes.

 

[JRouche]

So Im assuming when you say you arent getting any fluid to the back you mean while bleeding the back, pump after pump nuthing is coming out???

If so and it was a dry system it will take ALOT of pumping to get it back there. I have a vacuum pump, old medical surplus unit that I just hook up and pull the fluid through.

Now if the system wasnt dry, just bleeding to get rid of any bubbles up front from a MC change then even with a air pocket in there you should be getting fluid out of the rear bleeders. Then finally, after many pumps you get the long waited for surge of bubbles (air pocket) then yer just about home free.

You are bleeding the rears when you say you arent getting any fluid to the rear wheels right?? Yer not saying theres no fluid cause theres no brakes. LOL I know, obvious right, but you never know. JR

 

[tnblkc230wz]

While bleeding the brakes it is possible you tripped your proportioning valve. To check it, disconnect the brake light switch wire and put an ohmmeter on the switch contact and to ground. If you have 0 or near zero resistance, it is tripped. You will have to unhook the line going to the rear brakes and push the plunger towards the front of the car with a small, CLEAN, screwdriver. I had to get a power bleeder to bleed mine.

 

[fanbelt]

Make sure your bleeder screws are not clogged.

 

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still no joy...

Thanks for the tips guys. I'll check to make sure the bleeders aren't clogged.

tnblkc230wz...I can't seem to locate this plunger you mentioned. The pro/valve has a rear line coming into it (from the MC) and a line leaving it going to the rear brakes. The only port accessible is the line coming into it from the MC. I unhooked that connection and don't find a plunger. I can't access the other port without removing the assembly and your note seemed to suggest this is something I can do without removing the pro/valve assembly. (see photo)

I removed the MC again yesterday, and bench bled it again to make sure it was air-free and I think it is. The shaft got quite tight with about 1/8" of travel. No air bubbles. I reinstalled it and then tried to get fluid from the R/R wheel. None. Out of curiosity, I disconnected the rear brake line leaving the MC and pushed the brake pedal. No fluid exited the MC. How could that be? Does this sound like I need to adjust the brake rod length in my power booster? I measured to make sure it was the same length as the old one I replaced but maybe I'm off a little. Thanks for any other advice. I'm about to call in a professional. Anyone in the Nashville area want to make a little extra money? I've got the car on jackstands and all the wheels off! Thanks again,

 

[69AKDN]

Thanks for the tips guys. I'll check to make sure the bleeders aren't clogged.

tnblkc230wz...I can't seem to locate this plunger you mentioned. The pro/valve has a rear line coming into it (from the MC) and a line leaving it going to the rear brakes. The only port accessible is the line coming into it from the MC. I unhooked that connection and don't find a plunger. I can't access the other port without removing the assembly and your note seemed to suggest this is something I can do without removing the pro/valve assembly. (see photo)

I removed the MC again yesterday, and bench bled it again to make sure it was air-free and I think it is. The shaft got quite tight with about 1/8" of travel. No air bubbles. I reinstalled it and then tried to get fluid from the R/R wheel. None. Out of curiosity, I disconnected the rear brake line leaving the MC and pushed the brake pedal. No fluid exited the MC. How could that be? Does this sound like I need to adjust the brake rod length in my power booster? I measured to make sure it was the same length as the old one I replaced but maybe I'm off a little. Thanks for any other advice. I'm about to call in a professional. Anyone in the Nashville area want to make a little extra money? I've got the car on jackstands and all the wheels off! Thanks again,

I've had good luck gravity bleeding the system(s). You might be on the right track with the push-rod length. If it's too long will not allow the piston to retract far enough to expose the 'port'. Try adjusting your rod or removing it from your pedal completely....add some clear vinyl tubing ( so you can see what's going on ) and run the tubes from your bleeding screws into some jars or something....crack your bleeders screws wide open...top up your MC and walk away....check every now and then...top up as necessary....when you see a solid column of fluid in your lines you are done....close the screws....check the pedal. It's a 'painless' way of doing it by yourself other than using a mityvac to pull it through. If your 'idiot' light is not on your psi differential switch has not moved...The 69's have seperate proportioning valves..I belive they were called 'take up' valves back then...that is the seperate valve hanging off to the side of your MC.

 

[TizzDizz]

I've had good luck gravity bleeding the system(s). You might be on the right track with the push-rod length. If it's too long will not allow the piston to retract far enough to expose the 'port'. Try adjusting your rod or removing it from your pedal completely....add some clear vinyl tubing ( so you can see what's going on ) and run the tubes from your bleeding screws into some jars or something....crack your bleeders screws wide open...top up your MC and walk away....check every now and then...top up as necessary....when you see a solid column of fluid in your lines you are done....close the screws....check the pedal. It's a 'painless' way of doing it by yourself other than using a mityvac to pull it through. If your 'idiot' light is not on your psi differential switch has not moved...The 69's have seperate proportioning valves..I belive they were called 'take up' valves back then...that is the seperate valve hanging off to the side of your MC.

Cool. That sounds pretty painless, I'll have to try that. Does it actually work? I'd imagine it could be a good start for bleeding a dry system, then manually pump the brakes once it gets close.

 

[69AKDN]

Cool. That sounds pretty painless, I'll have to try that. Does it actually work? I'd imagine it could be a good start for bleeding a dry system, then manually pump the brakes once it gets close.

Works for me...it's all you need to do.