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...when is the last time you checked the fluid level? Sounds like the resevoir is near empty and you've started to pump air. It's probably a leak past the master cylinders' Rubber cup at the section of Cylinder which ends when Your pedal reaches 3 inches down towards the floor. A new Master may well be in Your future...
the bfluid level is where it should be...full.
there are no visible leaks at any wheel.

If the fluid were leaking internally, there should still be some loss even it was just a little between the mc and booster.

I think MJ is probably correct and one of the piston seals is bad and not pushing fluid which on retraction of the piston allows the fluid to remain in the system.

So...which mc do I order???
I have the same thing going on. I have looked at every brake line connection. No leaks. I have run a gallon of brake fluid threw it bleeding the calipers. I have those spring loaded bleeder screws so I don't have to involve her. I tried it the old way with her pumping the brakes and me loosening the screws. No bubbles either way. I replaced the master cylinder. The proportioning valve is gutted. No internals and sealed.

They pump up hard. Let it rest for a couple of seconds and the peddle goes to the floor. I'm stumped. HELP !!!
I blocked off the ports on the master and the pedalis solid. Then disconnected the line at the proportioning valve. The one at the top. I did not see ant air bubbles. I was then looking at the calipers in the front. One bleeder screw is towards the bottom and the other is more in the middle than at the top were I would expect it to be. I am putting the old style bleeder screws back in. And I am going to crack open the line towards the top of the caliper and try to bleed it there. And listen to my wife complain about pumping the brakes again.
you have a bad master. i had the same problem, drove me nuts and also to excessive consumption of adult beverages.

also, don't think that just because the m/c just got rebuilt it cannot be bad, mine was rebuilt and it was bad right out of the box!!

to test, try removing the m/c, put it in a vise, cap all the line ports and depress the plunger (?) with a clamp, it should lock up and then slowly loosen if the seal is bad.


I've used them and continue to use them without problems. However, if you put them on and for whatever reason take them off, put some thread sealer (Not Loctite) on the threads before putting them back on.

Originally posted by captaintobeys:
I will try that tomorrow. Has anyone had problems with the speed bleeders?
Yesterday I pulled the MC again. In the vise I first applied pressure to the piston using a socket and clamp. It held pressure. I then started pushing on the piston and noticed that I had no geyser effect in the rear chamber. I lowered the fluid level and still no geyser. The I attached fittings and hoses and compared the timing and amount of fluid flow. The rear chamber started late and had half the flow. I declared it defective. The parts store exchanged it for a new AC Delco. I ordered a pressure bleeder from Summit. This will mean no more wife in the drivers seat complaining about pumping the brake pedal.
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