The brake pedal has gone almost to the floor three different times on my son.He is very sure that it was not the clutch he was pushing.We just had brake work done and went back to have them bleed lines. Everything looked fine.What do I look for?
The brake master cylinder might be leaking internally. The next time brake pedal pressure is lost, pump the brake pedal rapidly. If pressure is restored, but then the brake pedal sinks slowly to the floor, the brake master cylinder requires replacing.
Tester
Then there is the possibility of the rear brakes being totally worn out. Drum brakes will leak when that happens and there won’t be enough fluid in the master cylinder to operate the front ones all the time. I’ve seen it happen before where the brake pedal goes down, then enough fluid slops over the wall and the fronts will work for a while.