Hydraulic Brakes 39 Ford.

[Phil Gillespie]

39 Ford Coupe Hydraulic Brakes .
The master cylinder to my knowledge has not been serviced/rebuilt.
MC is not leaking oil or overfilled.

Recently fitted a set of auto bleeders all round. Just the other day brake pedal came up really tight and brake lights came on. Also noted brakes were "on" without any foot on pedal. Released some oil out a rear bleeder and came right.
Brake light came on a day or so later sitting in garage.
Went round all brakes, bled them all and now brakes still work but needs about 1/2 pedal to engage. Previous approx 1/4 pedal travel for brake engagement.
My thinking is time for MC replace rebuild. Pedal travel has not been adjusted.
Thoughts, suggestions?
Phil NZ

[19Fordy]

First, try to adjust the pedal travel.

[Phil Gillespie]

Originally Posted by 19Fordy

First, try to adjust the pedal travel.

I did not want to adjust pedal travel as previously the pedal came up tight and brakes on. The reason for this? Fault in M/C? Normally pumping pedal gets brakes up tight at pedal but not this time.
Phil NZ

[Ideucev8]

You have to have free travel at your brake pedal for the master cylinder to work properly, to let he pressure out of the system. the brake pedal should move 3/4" before the push rod moves the master cylinder piston. I your brakes still come on after you have the free travel you have a master cyl problem.
Phil.

[Phil Gillespie]

Originally Posted by Ideucev8

You have to have free travel at your brake pedal for the master cylinder to work properly, to let he pressure out of the system. the brake pedal should move 3/4" before the push rod moves the master cylinder piston. I your brakes still come on after you have the free travel you have a master cyl problem.
Phil.

Thats what I'm thinking hence inquiry now on price of M/C & a M/C rebuild kit as this is an item not touched to date by myself.
Phil NZ

[V8COOPMAN]

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Are you sure that the pedal return spring is still pulling the pedal ALL the way back up? DD

[Phil Gillespie]

Originally Posted by V8COOPMAN

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Are you sure that the pedal return spring is still pulling the pedal ALL the way back up? DD

For sure as it returns all the way same height as clutch pedal.
Phil NZ.

[RKS.PA]

So, Phil, the only thing you did before this lock up started was to replace the bleeder screws with speed bleeders?

[Phil Gillespie]

Originally Posted by RKS.PA

So, Phil, the only thing you did before this lock up started was to replace the bleeder screws with speed bleeders?

Yes thats correct. And topping up brake fluid of course.
Phil NZ

[TJ]

You should have the vented cap on the MC. Are you sure the vent is clear?

[19Fordy]

This may sound silly but , is it possible to have created an air lock in the MC or somewhere in the system? We are all assuming that you used the correct bleeding procedure. I have bled the brakes on my 40 many times using Speed Bleeders with no problems. Hope you solve the problem.

[RKS.PA]

Originally Posted by 19Fordy

This may sound silly but , is it possible to have created an air lock in the MC or somewhere in the system? We are all assuming that you used the correct bleeding procedure. I have bled the brakes on my 40 many times using Speed Bleeders with no problems. Hope you solve the problem.

Also, might one of your speed bleeders be faulty? It has happened to me...the check valve isn't "checking" properly??

[Phil Gillespie]

Originally Posted by RKS.PA

Also, might one of your speed bleeders be faulty? It has happened to me...the check valve isn't "checking" properly??

Valid point re-check valve not checking. As instructions are to release only 1/2 turn for speed bleeders.
Phil NZ

[Phil Gillespie]

Thinking now I may need to recheck my use of the speed bleeders and only go with 1/4 turn open may have been a little heavy handed at 1/2 .
This is the easiest to check later on today.
Appreciate all the helpful and thought provoking comments
Phil NZ

[tubman]

I would think the only way the Speed-Bleeders could fail would be to leak, which should be obvious if that's what's happening. If they're not leaking, I can see no way they could add more pressure or fluid volume to the system.

Being an avid fan of Speed-Bleeders. I look forward to what you find.

[Mart]

Brakes staying on can only be caused by the recuperation port being blocked. either blocked by some debris or blocked by the piston seal not being clear of it at rest. The pedal may be level with the clutch, but does it come up further if you physically lift it?

[RKS.PA]

Originally Posted by tubman

I would think the only way the Speed-Bleeders could fail would be to leak, which should be obvious if that's what's happening. If they're not leaking, I can see no way they could add more pressure or fluid volume to the system.

Being an avid fan of Speed-Bleeders. I look forward to what you find.

Denny, agree about the leaking. And I, too, am a big fan...have them on all my cars. However, if the check valve fails to "check" couldn't that let air seep back into the system? I wouldn't necessarily see it because I'm in the car pumping the brake pedal?

[Phil Gillespie]

Originally Posted by Mart

Brakes staying on can only be caused by the recuperation port being blocked. either blocked by some debris or blocked by the piston seal not being clear of it at rest. The pedal may be level with the clutch, but does it come up further if you physically lift it?

Mart as you correctly point out the cause of brakes staying on as you state.
Pedal returns to floorboard underside and will contact here. This has been the norm for me. Will as above recheck again.
Phil NZ

[KiWinUS]

Piston in MC may not be returning all the way possibly created by rust or debris.

[1931 flamingo]

How about the length of the rod that goes into the cylinder from the brake pedal??
Paul in CT