brake light blues

[300kGN]

I replaced the powermaster, rear cylinders, and proportioning valve due to failing parts and maintenance. The rears are now 7/8"dia. I bench bled the master cylinder, I bled out all the wheels in sequence, I've bled the lines at the M/C, and prop valve. But the warning light still comes on everytime I release the pedal.
I've gone thru a gallon of brake fluid and it still sounds like bubbles are passing thru the prop valve. NO bubbles at the bleeders or anywhere else I open the system, WTF!
Anyone run into problems with larger wheel cylinders and the brass proportioning valve?

 

[zeus87gn]

The warning light comes on when you release the pedal?
We are talking about the red brake warning light in the dash?

I believe there is a wire connected to the prop valve.
Did you reconnect this? That may solve your light problem.

Have you cycled your accumulator? Air in there will cause the light to come on when you push the pedal.

Sometimes a new prop valve will need some reverse pressure to set the sensor. Have you tried backing up and putting on the brakes a couple of times? Be sure the wheels will stop before you do this...maybe sping the wheels off the ground and hit the brakes to verify.

Are you absolutely certain you got ALL the air out of the master cylinder when you bench bled with the key off? Did you do this on the car and reconnect the wheel lines as soon as you removed your bleeder lines? If you think you hear air, you probably missed some...somewhere.

Did you pump bleed the system? Sometimes pump bleeding will allow some churning of small air bubbles that may be trapped in corners (like in a new prop valve) and you get air all over the place.

Just offereing different possibilities....

 

[300kGN]

It seems like the valve is working and causing the light to come on. If I push the brake firmly and release the light comes on when I release. Then if I push the brake just a little (enough to slide the valve) the light goes out and stays out till I push firmly again. The pump and switch seem to be operating ok, although it is taking about 15 secs. to pump up the accumulator after discharging it.
The brakes are working as well as they ever have. Pedal is firm. I have about 1" of travel in the pedal before the brakes will hold the car in gear at idle. Definitely stops the car from speed.
The wire is connected, if it isn't the light functions on the pressure switch circuit of the P/M.
Bench bled on a vise (clamped to the pump motor bracket) with submerged hoses til no more bubbles flowed thru the hoses. Left the hoses on til the lines were ready to be attached. Gravity bled/vacuum bled til fluid came out at the wheels. Then pedal bled through 2 more quarts at the wheels, the prop valve and the M/C.
I think you're right that there're tiny bubbles trapped in the new prop valve. Just need to find a way to heave them out.
Regarding your system, when you're power-braking (at the line) can you feel a 2nd step in the brake pedal travel? Mine has always been this way.

 

[zeus87gn]

Hey there, sorry for the late response.

2nd step? Like you push the pedal until it stops and then it moves some more? Does it stop the car on the first try? Can't say I've ever heard of that before.
Only thing I can think of is the springs, valving and pistons inside the P/M aren't working together correctly. Did you clean the cylinder with a drying solvent like denatured alcohol?
Maybe a hanging rear cylinder due to a misaligned rear brake shoe?
Could be any number of possibilities.

15 seconds is a little long for the P/M motor to be running.
It this replacement P/M new or rebuilt?
have you cycled all the air out of the acc?

 

[300kGN]

Been busy myself, haven't had time to mess with it.

The car stops fine. When I'm building boost on the line, and have a lot of pressure on the pedal, I can feel a change in resistance as I'm pushing the brake pedal down (pushing way harder than normal braking). This P/M is a Cardone reman. The fluid in the accumulator res. is bubble/foam free.
Going to look into getting the acc warranted this week.

BTW, planning to deliver a '36? Chrysler to Atlanta after memorial day.

Thanks again,

 

[zeus87gn]

You may have something hanging in that fresh rebuild. It may go away after some time and use.

Where in the world did you find a Chrysler that old that is worth delivering to anywhere?

Atlanta is a little ways from me. I'm in Statesboro.