68 bleeding the brakes
Thread Starter
Heel & Toe
Joined: Dec 2020
Posts: 21
Likes: 1
68 bleeding the brakes
My 68 has been sitting more than 10years. I replaced the Master cylinder, new hoses and rebuilt all the calipers. Before installing calipers, I wanted to flush the brake lines. so fillied the master cylinder and all four lines disconnect from the caliper, no gravity fed fluid; pumping the brake pedal-- no brake fluid; blocked off the opposite brake line and with a brake bleed vacuum pump -- no fluid. I am suspecting the proportioning valve may be blocked in both directions?
Any thoughts?
Cheers,
Rick
Any thoughts?
Cheers,
Rick
Drifting
Joined: Nov 2013
Posts: 1,570
Likes: 485
From: Loud, Raw and Dangerous 1968 327 4S in Southern California
What does the petal feel like....perhaps the MC is not functioning and not allowing fluid to flow out?
Last edited by Redvette2; Jul 8, 2023 at 09:37 PM.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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Get a pressure bleeder and pump it up to 10 psi and start disconnecting your fittings and see where it starts leaking. The constant pressure will force the air out and let you know where the blockage is
1967 Pedal Car Champion
Joined: Mar 2020
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From: US-PNW
I'm thinking you have old jelled fluid in the system that needs to be cleared. Suction/sop up all fluid from the master's reservoirs and refill with denatured alcohol. Remove the lines from the master and see if the fluid escapes at the ports. Pump the brakes gently to flush the master's fluid passages with the DNA.
Remove all rubber lines at each wheel. Then using compressed air, see if you can blow through the two open lines that connect to the master. If not, remove the lines at the prop valve to see if they flow there. It's a matter of moving down the entire system, one joint at a time, to force out any gunk in each line.
If you can clear the entire system, flush it with a few fills at the master with DNA, then fill with cheap brake fluid and flush a bit more before bleeding.
