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View Full Version : Brakes feel weird after incorrectly bleeding - Is my master cylinder ruined?



MasterODisaster
10-27-2011, 12:34 PM
So I changed my rotors and pads and on one side the piston wouldn't go back in, so I released the pressure by opening the bleeder valve and apparently air got in, so I bled both front brakes with one of my friends using the pumping method, but I left the bleeder valve open the whole time he was pumping (found out this was incorrect later). I'm just wondering if he pushed the pedal all the way to the floor - did this ruin the master cylinder? Now when I push the pedal it travels too far before actually braking. Sometimes though if I pump the brakes it will feel correct for about 5 minutes, then the pedal pushes too far before the brakes come on again. I'm sure it needs to be bled properly again, but I'm just wondering why everyone says you aren't supposed to push the pedal all the way to the floor when using the pump method. I read about how the piston doesn't normally travel all the way to the floor in normal operation and that it can score the rubber seal if the fluid has been in there 5 years or so (I bought the car used so I don't know if they ever changed it). The fluid is tan colored, so I assume the fluid has not been changed for a long time. Car is a 2002 with 110K miles. I can't believe how complicated master cylinders and brake boosters are...

AKEP
10-27-2011, 01:38 PM
like vanilla envelope tan? thats normal. if its dark, like brown-black, then its contaminated. just bleed it correctly again. or get a vacuum pump/catchcan and do it that way. safer.

rex.effect
10-27-2011, 02:02 PM
If you open a bleeder without a vac attached, you will def. get air in there. The feeling you describe sounds exactly like air in the line. My STi did the same thing after bleeding the system after my SS lines install last weekend. I bled them again, now the pedal is nice and stiff again. I doubt any damage was done to the cylinder, but I couldn't say for sure.

Aren't you supposed to bleed the entire system, every time you bleed brakes? I thought just bleeding 1 or 2 was a big no-no.

MasterODisaster
10-30-2011, 06:40 PM
Yep - It was just my brakes needed bleeding. It made a HUGE difference. There was tons of air in there. Thanks guys!

rex.effect
10-31-2011, 04:59 AM
:wes: