Hello, I am new to this forum so please bear with me. I have a 1985, 240 GL Volvo. Recently I have had total brake failure on 2 different occasions. After the first time, my mechanic replaced the master cylinder and it seemed fine for several weeks. Then, one day while driving, I applied the brakes and it was as if someone disconnected the brake system, just a flat, to the floor pedal. I pumped the brakes, and it made no difference. I limped home and on the way suddenly, the brakes were back, and normal as can be. Again the master cylinder was replaced and for several weeks they acted normal (the brakes that is). Sat., after 2 hours of mountain driving, I was driving on a flat road, gently applied the brakes, and there were NONE. Again, as if the pedal was not connected to anything. I pumped them and they came back a little, but then total failure again. Again, while limping home, (I live in the semi-country) after about 5 minutes the brakes were back and acting perfectly normal. For some reason, it seems like it could be vacuum related. That some component sticks, when you pump the brakes you can hear air rushing, minutes later, they are back and working fine. I'm looking to sell the car, but not with this type of problem. Can anyone there help with this problem? Thanks in advance for any help you may provide.
Wayne