Last week I'm out doing some field work and Wednesday afternoon a rear brake line on my 40 springs a leak, one of the rear hard lines had broken. I had a replacement line but it was 200 miles away. As a field fix I crimped the leaking line and filled the reservoir with water and bled the remaining operational rear brake. This restored most of the braking on the Cruiser. I was pulling a boat so having brakes was kind of important. On the following Saturday I replace the broken line and bled the brakes. The only name brand brake fluid on the shelf was Prestone, but in synthetic, and that's what I went with. So after replacing the hard line and flushing the entire brake system the pedal is soft. I figured I had air in a line somewhere. Today I rebled the system, this time with assitance, and prior to bleeding I adjusted the rears. I had my son pump the pedal several times and hold it while I opened and closed the bleeder. We did this at each corner. While bleeding I noticed no air coming out of any of the lines. The rears had good pressure and each time a strong stream of fluid was expelled. Same for the the fronts but the flow was not as heavy. Almost an entire quart of fluid has been pushed through the system with the two bleeding events, and after all this the brakes are still soft. Any thoughts? I wouldn't think the synthetic fluid would be causing soft brakes, but could it? A cylinder freezing up with rust in only 2 days? Still some air in the lines somewhere?