Ok I'm lost, I had to take the brake line off my 32' Roadster to make some repairs. When I returned to bleed the bakes last week I could not get a hard pedal. I could pump them up and have a decent pedal but than if I waited a couple minutes , strait to the floor. I've tried a new M/C . I bench bled it well. bled all four corners and have zero air coming out. I've gone through the car to make sure there are no air or fluid leaks . I did replace the Proportioning valve (screw in style) before I started this. and it is fully open. The car had excellent brakes prior to this. It has four wheel power disc. 7" booster and Corvette 1"M/C .Any thoughts?
Another; "It worked good before I fixed it" topic. It has to have air in it somewhere. My favored method to bleed is to put a 3 to 5 psi on the master cylinder reservoir to push fluid through instead of pumping the pedal, Crack the lines at any junction blocks to let any air out before moving on to the wheels.
If it worked fine before, and the only thing you changed out in the brake system was the proportioning valve, then that is where I would look. Why was it changed? Is it a name brand one or a speedway special? I have used a few of the speedway brake valves, residual and proportioning valves, and they were always a problem. I had a residual valve, speedway brand, that would not leak fluid, But would **** air. Check you proportioning valve and all the fittings ***ociated with it. Id be willing to bet that's you problem.
Bleed the Wheel furth from the Master Cly. Right Rear, Left Rear, Right Front, Left Front & you should get a Pedal Just my 3.5 cents Live Learn & Die a Fool
The old Proportioning valve was leaking so it had to go. I don't remember where I got the residual valves from but I thought it was from Inline Tube. Maybe not a bad idea to replace them. Thanks for the advise.
Thanks for the advise, Pressure bleeding is going to be my next move. I just want to eliminate any potential air leaks first.
It goes to the floor with a 2ckt master cylinder? Sounds like lots of air in both front and rear brake lines. Probably not relevant esp since you've replaced MC's but do you have the right MC for the booster? They have 2 different types and if you have a MC for manual brakes the booster can't push it in deep enough.
In situations like this, I put wifey in the car and I start at the mc. Then down to prop valve, then EVERY junction in the lines going back. Repeat for fronts. Good luck
I ***ume you have a under the floor master cylinder any line that is higher than the master or the bleeder can be the problem., Raising the end or the car higher at the end you are bleeding can help or a power bleeder it does not give the air time to move back to the high spot between pumps. Also some of those through the tubing frame fittings can be a problem.
`I think the op said this started with removing the right rear brake line for some repair. I would think the air is trapped between the junction block for the rear flex line and right rear wheel cyl. with that being said back I'm the 70s when I worked as brake and frontend tech there were several cars you could only bleed with apressure bleeder. this could be the same deal. also a trick I found over the years when bleeding disc don't jam the pedal all the way to the floor. good luck hope you find it as this can be very frustrating. Tom
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