no brakes

[dbarker]

Ok here's my situation:

in 1998 a NEW (not rebuilt) master cyl. was installed by a professional. Had great brakes (not power, all drums).

Fast forward to now, The system had no ability to pressurize. (ie pedal went to floor and back with zero resistance) I checked the fluid levels, both front and rear were low (rear was way low but still wet). I cleaned out the old fluid and refilled the cyl with fresh.

Pumped the pedal some and got great pressure... takes about 10 pumps, but that thing gets great pressure (way better than my 94 F150 ) Had my friend go to full pressure and hold it while I looked for leaks and found none.

Pulled the right rear tire and performed a brake bleed..... absolutely zero fluid came out.... nothing nada zilch. Pedal also did not sink when i popped the valve open
Went to the right front.... cant get the bleeder to open...

SO, what's my next step? The brake lines arent pinched shut. They arent leaking. Could they have clogged just setting with the system closed and ok fluid in the lines? There was no rust inside the master cyl.

Thanks everyone! ( for another puzzle see my thread in the engine section )

[fordman]

a 1998 with drums? soudns liek it might need wheel cyilnders. if fluid doesnt come out of them that is why the no brake thing. the lose of fluid will probably be found when you replace the wheel cylinders. push the brakes real hard before you go in for the night. come back out and look on the inside of the tire for wet spots running down from the drums. that will tell you which one is leaking.

[dbarker]

no in 1998 it got a new master cyl. the truck is a 68.

I've leak checked. No leak anywhere. Over a 3 week period now.

no idea how to replace wheel cyl. I cant even get the drums off to check the pads.

[fordman]

look under the carpet or mat. the master may be leaking into the cab. or it could have the mystery leak my 67 has. which i cant find either. the brakes are good and then after it sits no brake fluid and no leaks found. wierd.

[dbarker]

no leaks. i'm keeping an eye on the level in the cyl itself.

It set for 13 years. the fluid evaporated mostly. like i said, both reservoirs had fluid.... just one was lower than the other.

[70_F100]

The holes in the bleeder screws are most likely plugged.

Pull the screws and clean out the holes and passages with some stiff wire, or, worst case scenario, a drill bit (make sure it's smaller than the existing hole).

[chiggerranch69]

Try to unscrew the bleeder all the way out and check the hole on the bottom. I have seen many bleeders (including my 69) that were full of rust and hose lining that prevented any fluid from being pushed out. You can use an 1/8th drill bit by hand to clean out the bleeder. As for the leak, if the fluid level became low, there has to be a leak somewhere, as a braking system doesn't "use up" fluid. I you are pumping the brakes 10 times then you have air somewhere.

[dbarker]

well like i said, the truck set for 13 years. the low fluid was probably caused by evaporation. It was about half full in the rear and 3/4's full up front.

I've pumped the brakes up to full pressure, and held them for 15 minutes solid. I've repeated this at least 5 times. No fluid loss in the reservoir at all. No brake fluid under the carpet, no fluid under the truck, running down the tires or anything.

I'll check the bleeder valves for a blockage. I havnt opened the right rear one very far, I may have not opened it far enough to begin with... I turned it a quarter turn (per a video i saw) ill open it up full tilt and see what happens.

[chiggerranch69]

Full pressure should be acheived with just a few pumps of the pedal. If that is not the case then you have air in the lines or master cylinder. You could try to break the lines loose at the master cyl. and slowly apply the pedal to push any air out, but be sure to close the lines up before relesing or you will suck air back in.

[bluemoose]

To take off the drum:

Jack and remove wheel.
There is a rubber stopper on the rear bottom of the brake assembly (back).
Take that out and shine a flashlight inside.
You will see a sprocket like device.
Use a brake tool, or a wide blade screwdriver to turn it ( it should turn upward).
This will retract the shoes and allow you to pull the drum off.
You may need to hit the outer rim of the drum with a hammer to break it free.

Hope that helps

Moose

[fordman]

dont hit it too hard. it could break. the back drums are sometiems haed to remove with the rust in around the center of the hub.

[QC]

If it sat for 13 years the wheel cylinders are probably rusted solid. Regular brake fluid absorbs moisture out of the air and it settles in the low spots. If a vehicle is going to sit most of the time you should use silicone brake fluid. It does not absorb moisture.