67 m715 brake pedal to the floor

[racingjoe66]

Okay guys, I am having an issue with my 67 m715 kaiser. The brake pedal goes all the way to the floor. It has been sitting for a couple years as I bought a new place and haven't had time to drive it. Anyway I checked the fluid level and it was dry so I filled it up with fluid and I have pumped and pumped and pumped the pedal and still no pressure at all and the fluid hasn't gone down. Any suggestions? It is all bone stock the truck.

Any help is greatly appreciated. Want to get it up and driving again

[Mikel]

Did you open the bleeders in the wheel cylinders?

[racingjoe66]

No I didn't, I figured pumping it before opening them up would still build up some pressure?

[Mikel]

No I didn't, I figured pumping it before opening them up would still build up some pressure?

You may have too much air in the system for that to work.

If your master cylinder drained, the leak must be quite apparent, so you know what to fix.

[NOLA5Qtr]

You need to open the cylinders and bleed the brakes to get the air. There must be too much air in the system.

[MrNeutron]

Your master cylinder piston might be stuck due to corrosion in the bore. That's what I found on my truck when I bought it and it had been sitting for 5 years.

[Von]

I was going to guess that the seals in the MC shrunk/dried out while sitting and the fluid drained out onto the inside of your firewall.

But when that has happened to me refilling the MC and pumping it up worked... because the leak is at the top of the system. Must be leaking further down stream.

You have any fluid leaking down the inside of any of your tires? Maybe a wheel cylinder seal let go. Or one of the rubber hoses.

If it's been parked on grass or dirt it's probably impossible to tell where it's leaking ... and if it leaked out a while back and dried up... But now with fresh fluid in it to leak out it might be easier to track down.

[racingjoe66]

I did notice after I filled it up and was pushing the pedal by hand to pump it that there was a drip from the bottom of the master cylinder where it comes through the firewall on the inside of the truck. Is there a way to replace the seal or best to buy a new MC?

[racingjoe66]

And yes it was parked in the grass and I didn't see any other places that looked like they leaked at all.

[Don Cavey]

At the risk of raining on your parade, I think you may have to rebuild the master cylinder and the four wheel cylinders. No doubt, from sitting, you have a mess in all of them and if rusty (probably), they won't rebuild without leaking.

Yes, lots of work but one thing at a time and you are good to go.

Sorry if I offended; it was unintentional...