Reader Question Austin,
I have a 1999 Oldsmobile Alero,Just replaced the Master Cylinder,and the mechanic told me that he did bleed the lines , when I drive and come to a stop light, with my foot on the brake it still slowly goes to the floor still, I thought that problem was solved,what else cloud it be? The fluid is leaving but we see no leak can you help,where is the brake fluid going?
If you took off all 4 wheels and you do not see a sign of a brake fluid leak externally, then I would suspect you STILL have a brake master cylinder problem. A common symptom of a brake master cylinder that “bleeds down” internally is when you are applying constant pressure to the brake pedal and the brake pedal “fades” sinks to the floor. You can usually pump on the brake pedal a few quick times to build up internal pressure again. I would try another cylinder if you don’t have any external leaks.