How do you know if the Master Cylinder is faulty? HELP!!?

(2011-06-25 14:20:23)

1. Les Halles Says: Ok. So I bought a car the other day and the owner told me it needed a new master cylinder cause when you brake, you have to push the pedal ALL the way to the floor until you get any brakes (and even then, the brake sucks). It wasn't leaking or anything but I know that often times, the Master Cylinder will have an internal leak. So I took it off, but the piston was still firm. Could it be the inner piston and/or grommets that are causing it, or do you think the Master Cylinder is fine? How can I know (just by looking at the Master Cylinder itself) if it is faulty?

THANKS!

2. bobweb Says: Assuming there are no fluid leaks, you first need to know that the brake lines don't have any air in them and need bleeding. If your friend says he tried to bleed the brakes and failed, then first have the brakes bled. If the brake pedal still goes to the floor, the symptoms are those of a bad master cylinder.

3. loonatic72 Says: You could try bleeding the whole system and replacing all the brake fluid. It could have air in the system and the old fluid could be breaking down. When you drove the car could you pump the brakes and get brakes? Usually if a master cylinder is bad you can pump the brakes and get brakes but as you hold the pedal it will go down.

4. Michael S Says: You should stop playing with your brakes if you don't know what you're doing.