nitroxsteve Posted February 13, 2012 Share Posted February 13, 2012 I have had both sides of my brake master cylinder go dry twice. It takes a very long time to go down and I have not found a leak. All four corners are dry and I have followed the lines and no leaks. Can it drain back into the booster? I have seen this happen on older cars but only on the back side of the master cylinder not both sides. Thanks, Steve Quote Link to comment Share on other sites More sharing options...
jimoshel Posted February 13, 2012 Share Posted February 13, 2012 It can drain back into the booster, both seals bad in MC but that is very improbable. Pull the vacuum line from the booster and see if there is any trace of fluid. Recheck your wheel cylinders. A leak that slow would get covered up with fresh brake dust and not show as a fresh leak. Quote Link to comment Share on other sites More sharing options...
AMCJeepMJ Posted February 13, 2012 Share Posted February 13, 2012 Your brake fluid level will drop as your pads and shoes wear down. Quote Link to comment Share on other sites More sharing options...
nitroxsteve Posted February 13, 2012 Author Share Posted February 13, 2012 It can drain back into the booster, both seals bad in MC but that is very improbable. Pull the vacuum line from the booster and see if there is any trace of fluid. Recheck your wheel cylinders. A leak that slow would get covered up with fresh brake dust and not show as a fresh leak. Would the rear slave cylinders allow both sides of the master cylinder drain? Quote Link to comment Share on other sites More sharing options...
nitroxsteve Posted February 13, 2012 Author Share Posted February 13, 2012 Your brake fluid level will drop as your pads and shoes wear down. Yep but I have only put around 3,000 miles on it in the last year and all brakes are new. Also it drains competely empty. Quote Link to comment Share on other sites More sharing options...
jimoshel Posted February 13, 2012 Share Posted February 13, 2012 It can drain back into the booster, both seals bad in MC but that is very improbable. Pull the vacuum line from the booster and see if there is any trace of fluid. Recheck your wheel cylinders. A leak that slow would get covered up with fresh brake dust and not show as a fresh leak. Would the rear slave cylinders allow both sides of the master cylinder drain? No. There is a seal between the two master cylinders. Both seals would have to go bad. You will notice one of the master cylinders is larger than the other. That one is for the rear brakes. The smaller reservoir is for the front brakes. That is, if you have disc brakes in front and drum in back. Normal shoe wear will lower the fluid level. Not empty the reservoir. Quote Link to comment Share on other sites More sharing options...
carnuck Posted March 8, 2012 Share Posted March 8, 2012 It can drain back into the booster, both seals bad in MC but that is very improbable. Pull the vacuum line from the booster and see if there is any trace of fluid. Recheck your wheel cylinders. A leak that slow would get covered up with fresh brake dust and not show as a fresh leak. Would the rear slave cylinders allow both sides of the master cylinder drain? No. There is a seal between the two master cylinders. Both seals would have to go bad. You will notice one of the master cylinders is larger than the other. That one is for the rear brakes. The smaller reservoir is for the front brakes. That is, if you have disc brakes in front and drum in back. Normal shoe wear will lower the fluid level. Not empty the reservoir. Backwards. Larger rez is front because the disc brakes require more fluid due to wear and tear. I've had the master throw fluid over the "wall" between front and back and empty both. Quote Link to comment Share on other sites More sharing options...
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