1996 honda accord, recent purchase for my daughter away at school. about two weeks go by and she tells me the brake light came on a week ago (typical of women) anyway get car home sure enough no brake fluid in master cylinder. im figuring a leak somewhere, refill and bleed system, drive around for a while, back at home inspect all lines,calipers etc... no leaks. i trade cars with her and drive to make sure ok, couple of days go by and brake light comes on again, check and fluid gone again,still cant find any leaks though. fill and bleed again, this time pedal goes all the way to the floor after bleeding, im sure i got all the air out, fluid topped off, no brake light this time, but pedal goes all the way to the floor before car will stop. at my wits end cant find a leak and brakes not working. could it be the mastercylinder and where is the fluid going if i cant find any leaks.

 

Check master cylinder (MC) for leakage. MC may be leaking at mating point w/ vacuum brake booster and fluid is trapped between brake booster and MC. A cracked vacuum brake booster diaphragm might suck brake fluid from the MC.

Have you looked at all brake lines along the body for evidence of leakage? I had a Dodge PU brake line corrode to a leak due to salt water exposure (beach).

Fluid is ether leaking or being pulled into engine through vacuum brake booster.

good luck

 

thanks, upon further inspection if found the leak in the brake line, corroded from snow salt.