radman3120 Posted May 21, 2009 Report Share Posted May 21, 2009 I hadn't driven my '93 Z34 in a while except for autocross like a month ago so I decided to take it out last week. I was driving along and started to feel the brakes fade away. Every time I hit the brakes the pedal went lower and lower to get the same effect until it was going to the floor so I pulled off at an intersection to check it out. It felt exactly the same as my truck did when it blew out a brake line not too long ago but I couldn't find any brake fluid anywhere. Since I wasn't too far from home, it was only back roads that I was on, and my car is 5 speed I decided to just limp it home. I just parked it and grabbed another car because I had things to do. Now the other day when I was at school my dad and grandfather decided to check it out and see if they could find where the brake line was broke but when they started it up it had full brake pedal. I took it for a fairly long test drive last night and it acted 100% normal. Any idea what this could be? Power booster going out and just working intermittently? I couldn't find any vacuum lines or anything disconnected. My grandfather did say he plugged some sort of sensor in that was hanging underneath the car when he was looking for brake fluid but I don't know which it was. Quote Link to comment Share on other sites More sharing options...
Leadfoot Posted May 21, 2009 Report Share Posted May 21, 2009 Sounds like the booster. I had that happen before and replaced the booster, then it never happened again. I never found a good way to test it that I trusted so I just replaced it. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted May 21, 2009 Report Share Posted May 21, 2009 I vote master cylinder. I had the same thing happen to my '91 CS. Had my master cylinder replaced, and that solved the problem! Quote Link to comment Share on other sites More sharing options...
Crazy K Posted May 21, 2009 Report Share Posted May 21, 2009 this is a weird one... I don't know what should be replaced... but the MC sounds like the culprit, but the vacuum booster does not. if it were me... I would do a total system bleed, and do a "stationary performance test" of the brakes, meaning you slam them as hard as you can a few time in a row with the engine running but the car stopped to simply cycle the system and see if something breaks. better that it break while parked then in an emergency. It's possible that nothing else will ever happen. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted May 21, 2009 Report Share Posted May 21, 2009 this is a weird one... I don't know what should be replaced... but the MC sounds like the culprit, but the vacuum booster does not. if it were me... I would do a total system bleed, and do a "stationary performance test" of the brakes, meaning you slam them as hard as you can a few time in a row with the engine running but the car stopped to simply cycle the system and see if something breaks. better that it break while parked then in an emergency. It's possible that nothing else will ever happen. "stationary performance test" i did that and blew 2 brake lines... . but yes, reiterating what Crazy K said, safety is much more important than saving a few buck/minutes of time. much better to get it worked out now, rather then when you NEED brakes. Quote Link to comment Share on other sites More sharing options...
radman3120 Posted May 21, 2009 Author Report Share Posted May 21, 2009 yea, i am afraid to drive it if i don't do anything to it because that means it could happen again or get worse. i would much rather something break that way i know it was the issue (or part of it) lol. ill start with crazy ks suggestions and go from there. Quote Link to comment Share on other sites More sharing options...
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