URGENT!! 96 4X4 Brake Problems

[TwoShort]

I have a 1996 Explorer with ABS and 4 wheel drive. I just recently (about 45 mins ago) encountered brake problems. When I'm driving, if I push the brake pedal it's a bit soft, but will stop the car, as long as I don't pump it. If I pump it at all it goes to the floor within about 2 pumps and i have no brakes. If I pump the pedal when the engine is off I have pressure and lots of it. What could 'cause this? I'm afraid the mechanic is just going to replace the master cylinder. Is that necessary, or could it just be that the fluid has never been changed? Could it just be air and moisture in the lines, or is this a pretty sure sign that the master cylinder is dead? It's going in in a few hours (I can't be without a car), so any help would be appreciated. Thanks

 

[jayhawkexplorer]

It sounds like air in the lines...

 

[Skibug]

Try bleeding them. Like said above, sounds like air in the lines. If you are by yourself get a simple brake bleed kit from an auto parts store to make it easy. They are only like $6.00, at least the one at autozone I got was. Check all brake hoses and connections to make sure of no leaks. Then if this does not fix problem, replace the brake lines if this has not been done. I have seen brake lines create pockets in them and would obstruct the fluid. If this does not fix the problem, it could be the master cyl.

 

[Positive Vibes]

You did check the fluid level? Not sure about the air theory unless there was work done on the brakes recently. Check for leak theory sounds better, if you have a small leak it will loose pressure. Was there any work done on her recently?

 

[TwoShort]

There was no work done recently.. Turns out the master cylinder was shot. $235 later...