Major issues with brakes ?????

Here we go...

What I have:
'59 F100, rear drum/front power disc conversion from '71 Lincoln including booster and master cylinder and block, late '70's Ford rotors & new mid '80's Chevy calipers. Newer brake lines.

Problem I have:
When truck is not running, pedal is somewhat stiff but doesn't build up pressure with more pumps. When running, the pedal goes all the way down and finally stiffens when about .5" away from floor, at the same time you hear a lot of air in the pedal movement. When truck is in gear, it barely stops from a roll.

What I have done:
Bled the brakes from pass. rear wheel, to rear driver, to front pass., to front driver. All flowing good and without air. No visible leaks anywhere.

What I'm thinking:
If the master cylinder was bad and leaking around the seal, I would notice fluid loss either in the cab or the outside firewall and there is none. On the other hand I'm not sure what I would encounter if the booster was bad.

Opinions welcome.

I'd try a new master and see what it does.

The master cylinder can be bead and not show fluid loss - The seal on the piston can be bad causing it to push through the fluid.

Andy my dad had a truck chevy of course we did the same thing to it.If you are hearing alot of air when you push the pedal it was the booster that was bad on his.If its not running no matter what the pedal is going to be stiff because its not getting any vaccume

the vac . booster is bad and possiblly the master also seperate them and see if there is fluid in the inside of the booster but i feel its most likely you have a bad booster

You guys ready for this one????

Of all the things that the builder did to this truck that is top notch work, I would never have thought that I would have found what I did! The elbow that is connected to the booster and vacuum hose that is in turn connected to the intake, YEA! The rubber "seal" around that elbow that wasn't creating a seal... YEA!!! WAS A FLIPPIN PIECE OF GARDEN HOSE!!!!!!!!!!!!!! Needless to say...... brakes are good NOW!

Just kinda curious if the shaft is okay to put a new master cylinder on? Was not sure if the rust would be an issue.

Clean the flake off, Steel wool or SOS pad, shoot some wd40 on it and stick it on.

that rod will pull rigt out real easy

I was just thinking, if the master cylinder was bad, wouldn't there be fluid in the booster? Just trying to narrow it down since I want this issue to be done and over with instead of spending more time on it.

No.. A master can go bad and not even leak sometimes. It will bypass from the inside. It may not be what the problem is but that is the first place I'd start.

RebStew wrote:No.. A master can go bad and not even leak sometimes. It will bypass from the inside. It may not be what the problem is but that is the first place I'd start.

Kinda like what I said...

Blue Eyed Devil wrote:

RebStew wrote:No.. A master can go bad and not even leak sometimes. It will bypass from the inside. It may not be what the problem is but that is the first place I'd start.

Kinda like what I said...

yeap

RebStew wrote:yeap

And you too! Haha...

just makin sure guys, just makin sure

You don't know how frustrated with this I am. Being that we are down to only the family van and having to nickel and dime this thing, it's really starting to stress me.

Which is why NOW is a good time to replace the master cylinder. They are cheap. You have the system torn apart, so no reason not to. Go ahead and do it now, bleed everything out and be done with it for a while. Your safety (and others on the road) isn't worth a few bucks saved...

Blue Eyed Devil wrote:Which is why NOW is a good time to replace the master cylinder. They are cheap. You have the system torn apart, so no reason not to. Go ahead and do it now, bleed everything out and be done with it for a while. Your safety (and others on the road) isn't worth a few bucks saved...

Replaced the master cylinder and lines to the valve, and not only do I not have a little bit of brake pedal, but nothing at all! No fluid coming out of bleeders at all. And there is still that "air flushing" sound when the pedal is pressed. I'm seriously about to drain the oil and crank it over and hold it at about 8000 RPM till it makes some heavy metal! Not really.

Did you bench bleed the master cylinder before installing it?

What does your weekdays look like? Are you free through the day? I have a meeting Wensday but I think I can clear a day to stop up. I think it may be something you are overlooking. You should be getting something out of the bleeders. Did you ever get anything out of them?

Blue Eyed Devil wrote:Did you bench bleed the master cylinder before installing it?

As long as he didn't run copper brake lines on it it should work. Right?? LOL
Inside joke fellas.lol
That poor guy. I feel sorry for him. Not really
Yeah I know I'm a trouble maker..

Andy if you are free I can come up sometime next week and try to give you a hand.

Thanks Steve for the offer. Let me see what I can get done with it tonight and then go from there. I will let you know.

Well, I went home and took it off AGAIN, and re-bench bled it AGAIN and it still is not building up pressure. And it is still making the "rushing air" sound when the brake pedal is pressed. This air is noticeable when sitting in cab but not outside of it. Any ideas now?

You must be gettin air back in the system if you cant build up any preasure......