[klutchmaster427]

On Sunday I towed a 1986 cougar home from my friends house. It has a blown head gasket, so I could run it for a little bit but then I'd have to shut it off so it doesn't over heat. the problem with that of course being the issue of no power brakes while being towed 10 feet behind a truck that your wife feels needs to be going 40. lol. anyway, I had to really put my foot in it to get stopped without rear-ending my own truck a couple times. we finally got it home and parked it, and now when i push the brake pedal it goes straight to the floor with hardly any resistance. when i push it in, you can hear the sound of air, like when you pump the old school bike tire pumps. i took the cap off the master cylinder, and when the brake pedal is depressed you can see a small ripple on the top of the fluid, but it doesn't spurt like it should. What did I break????

[smrat]

maybe a broken line. remember to check the high spots along the top of the frame where the line runs as the fluid will run to the lowest point. or u could have blwon the master cylinder

[eloc431962]

I agree, A bad master cylinder or leak in the brake system will cause pedal that goes to the floor. Cole

[klutchmaster427]

Originally Posted by smrat

maybe a broken line. remember to check the high spots along the top of the frame where the line runs as the fluid will run to the lowest point. or u could have blwon the master cylinder

A broken brake line was my first instinct, but no matter how much I pump the pedal, the fluid level in the master cylinder stays the same. completely full. I was planning on replacing the master cylinder, but I figured I'd post something here in case it could be something else because I don't really want to buy a new one and replace it if mines fine. When i take the cap off the MC, and have someone push the brake, the top ripples a little bit...but it doesnt squirt. its like its moving a little bit of fluid but not much. Could it be that a seal in the mc could be blown and the fluid is just passing the valves and going straight to the lines? maybe?

[scrot]

Your system could be full of air, or the piston inside the m/c is stuck.
I just replaced the m/c on an '87 Ford. I took apart the m/c to see what was wrong (I'm like that). I expected to see the rubber seals worn or scratched, or the bore pitted and scratched. The seals were as good as new, and the bore wasn't pitted at all, but what was bad was the bore. It was actually rusted in spots even though of course it was full of brake fluid. There was enough moisture there to rust the metal in spots . The rusted areas were actually higher than the rest of the bore. When the piston seal moved over that area, the pressure leaked around the seal.
I learned another think first hand. The metal was clean in most areas, but in between the seals where they never passed, the metal was quite rusty and scaly. If the m/c were pumped with full strokes, the seals would get scratched and damaged by the rust. In the future when I bleed the brakes, I'll use short strokes unless the m/c is new.

[427v8]

Since you can't pump it up and you're not loosing fluid, I vote for the Bad Master Cylinder.

[T-bucket23]

If you get some plugs the right size you can remove the lines from the master, install the plugs and see if you have a pedal. We have a kit with all the different plugs. It has saved replacing a lot of masters that were not defective. If you cant find plugs you can make them from brake line fittings, just braze or sliver solder the holes closed.

[klutchmaster427]

hey thanks a lot i'll try that. save a lot of work if the master cylinder isn't bad!