Trying to bleed the brakes and having a problem I hope someone can figure out. We are doing it manually the old fashioned way with one person pushing the pedal and the other opening and closing the bleed valve. I have done this before on other vehicles and in fact it worked fine on the front brake system. (I have installed another reservoir to make the two systems fully independent, front and rear.) We have been pumping on the rear system for over three hours and have pushed over a half a gallon of fluid through it. We are still getting bubbles out of both sides of the rear brakes. Here's a clue that I do not think is normal. When the pedal is depressed, nothing happens in the reservoir (which I think is correct) but when the pedal is released, air bubbles come out of the hose into the reservoir! I just noticed this when trying to figure out where all the air in the line was coming from and I do not remember every seeing this before. It appears to me that the cylinder is somehow sucking in air and releasing it into the lines and back into the reservoir, however there are no fluid leaks whatsoever anywhere in the system. So, what is wrong?