Sorry, to contradict all the advise everyone is giving you, but I think I have a different reason for this problem. I think it is the master
cylinder that is dead. The pop you heard might have been the internal piston seal going. There are several good reasons for my
saying this. First, if it was just the bleader screw, or any other component on that rear drivers side break, you would still have the
front breaks working. This is because modern jeeps (is any such thing) have two seperate brake systems. One that operates the
front brakes and a seperate one that operates the rear breaks. (therefor the two seperate bowl sections) The idea being that if you
lose one system the other still works. In order for your breaks to totally fail like that you would have to lose break pressure in both
systems at once. This is not very likely. Especially when you figure that at least one of those component failures would probably
mean dumping your break fluid on the ground, and not leaving it sitting in your bowl. If the master cylinder piston seals breaks then
the pedal could easily go to the floor. This is because, in effect the piston would just be swooshing the fluid around in its bore
without actually creating any fluid pressure on the breaks. It is posssible that the leak at the rear could be just some spilled fluid
from your prior break job. There is also the possibility that it is a seperate smaller problem.
This could not be the bleed screw,because if it was you would have pressure until the bowl was dry.
This could not be the booster, because if it was you would still have breaks just very week ones. Like when the engine is off.
The only other possible cause could be that you had a mechanical break in the pedal assembly. I have rebuilt these and I don't find
that to be likely. Can't hurt to look though.
On the up side master cylinders are cheap. I used to work for a parts store, and most were in the $20 range for a rebuild one. You
could even rebuild it yourself for about $10, but don't do that unless you like to take the hard way. I even have one off my 83' CJ7
that you can have for $10. I would buy a rebuilt one though. You will have to bleed the entire system when you do this, and I would
suggest you think about servicing all your breaks now as bleeding them is half the work.
Ethan
I know this may be jumpy. I was interupted several times while writing this.