Hey all,

I have had this issue to some degree for a while, but after the truck sat for a bit it seems to be much worse. When I finish driving, I have noticed that the front reservoir of the master cylinder is pushing fluid out from under the cap. When I looked today, the reservoir was three quarters empty. I put a new gasket in the cap, but that didn't make a difference. I assumed that there must be something blocking the lines down from the master cylinder but the rear brakes have been bled recently.

This truck has no power brakes, and it front disk and rear drums. The master cylinder has two reservoirs, the front is small and the rear is large. I am trying to think of any other info that might be helpful.

Thanks,
Sam

 

Is this the only problem? Do the brakes operate fine otherwise? How is pedal pressure?

 

Pedal pressure isn't perfect. It can be a little spongy but one pump brings it back. I did have the pedal sink a bit the other day. I pumped it back up, and it held firm after with consistent pressure. That is what made me look in the reservoir.

Sam

 

As you work the brake pedal there is a little "old faithful" geyser inside the reservoir. If there is any weakness in the seal it will get out. I have found the problem on re-pop masters is the wire bail that holds it all in place. It sometimes needs "tweaking" to keep a consistent pressure against the seal front and back.

 

Do you have rubber brake lines going into the front calipers? How old are they? Check them for cracked-ness, brittle-ness, etc.

They might to "look" fine at a casual glance, but over time, the rubber innards will bung up causing problems.

Read the post by Alchemist1.
https://www.ford-trucks.com/forums/1...-sticking.html

 

How does the sealing surface of the master cylinder look? Mine was leaking fluid and I had no success with a new gasket either. I put a straight edge across the sealing areas and noticed some gaps. Plus the metal was corroded. After getting a new one from Napa, I could see a huge difference in how much of the master cylinder was in contact with the gasket. Basically the new one had a nice milled surface while my original one had a rounded contact surface. Long story short, this solved my leaking problem.