Brakes Going To Floor

[MSwheelin]

I had not driven my 66 in a while, and I took it around the block yesterday and noticed the brakes go to the floor. It stops but barely. I checked the master cylinder and it is dry, but there is no evidence of fluid leaking anywhere.

Can I just add fluid back to the master cylinder at this point or is there more involved?

 

[DirtDonk]

It will at the very least require a full bleeding. There is already air in the system unless you still have a bit of fluid in the reservoir, but anywhere near the bottom and you're just better off bleeding everything and purging all old fluid anyway.

So do the usual, and fill the reservoir, then start at the right rear, then left rear, then right front, then left front wheel cylinders (or calipers if you have front discs yet).
This way you'll not only have all new fluid, but all the air will for sure be gone.

At this same time, and really before you've finished your bleeding job, you should have inspected every line, fitting, caliper/wheel cylinder for any sign of leakage. No sense in bleeding the full system if you're still going to have to replace an old worn out and leaky part.

Paul

 

[DirtDonk]

How long was it sitting? I've seen masters go dry from sitting too long even without obvious leaking anywhere int the system.

AND(!) you should decide if any of the parts are old enough to warrant replacement out of hand anyway.
If the master is original for instance, even if the vehicle only has 40,000 miles on it, it would seem to be to be time to replace all the wear parts due to age alone.

Paul

 

[Broncobowsher]

Full bleed. There is air in the brakes now. These are hydraulic brakes, not air brakes.

The brake fluid did go someplace. It might even be in the cab. when the master cylinder goes it can leak to the pushrod, and that is under the dash.

Wheel cylinders could have gone bad as well. With enough brake dust it might just be goo inside the drums. Are the brakes adjusted right (Isn't the '66 manual brake adjustment?), or are the self adjusters working right? You might be to the point that the wheel cylinders are at the end of the range and are starting to blow apart. That's why the brakes have to be adjusted, only so much stroke in the wheel cylinders.

 

[pipeline010]

Full bleed. There is air in the brakes now. These are hydraulic brakes, not air brakes.

The brake fluid did go someplace. It might even be in the cab. when the master cylinder goes it can leak to the pushrod, and that is under the dash.

Wheel cylinders could have gone bad as well. With enough brake dust it might just be goo inside the drums. Are the brakes adjusted right (Isn't the '66 manual brake adjustment?), or are the self adjusters working right? You might be to the point that the wheel cylinders are at the end of the range and are starting to blow apart. That's why the brakes have to be adjusted, only so much stroke in the wheel cylinders.

Recently my brakes did the same thing. As bowsher mentioned above, the culprit was a blown rear wheel cylinder. The fluid wasn't obvious until I pulled the drum, but every push of the pedal spewed more out. Changed the wheel cylinder and all was well.

 

[B RON CO]

Hi, right now the Bronco is too dangerous to drive.
Are you going to fix it yourself, or take it to a mechanic?
The brakes must be inspected for where the fluid loss is.
For all you know, you may need all new wheel cylinders, maybe hoses too.
Rusted and stuck wheel cylinders are relatively common.
Good luck

 

[MSwheelin]

Going to replace the master cylinder and inspect the cylinders at each wheel. I see some fluid around the rear driver's side wheel which I thought was a leaking axle seal but now suspect it could be the brake cylinder. It does have the self-adjusting brakes which makes it easy to get it right once everything is working properly. Thanks for the input.

 

[Pa PITT]

.. Mine leaks a lot of fluid .. But since mine stays on the farm 99% of the time . So I just add fluid & it goes back to work . I believe I've put on about 6 M/C So Now I just add & check regularly.
Now I was going to town every day . I'd put in a new system I GUESS But I've not found my leak.

 

[Skytrooper15]

Now thats a feeling that makes you think about going home and changing pants when the brake pedal hits the floor.I let mine sit up without driving it much for 12 years just cranking it up on occasion and mine was gone also and I have yet to find the leak but am still looking and checking the fluid level.I go along with all of the experts above my post,bleed the brakes and check for leaks and replace anything you are in doubt about.