brake problem
 

a friend of mine's got a 90 civic si with a wierd problem when the temperture rised the brake pedal goes to the floor (on the way to work its fine on the way home it happens) i've changed both wheel cylinder and both calipers. the brakes have been bled about 3 times. there is no air in the system or leaks what so ever.
any advice would be appreciated.
thaks

what happens if you pump it up? notice any leaks? brake fluid full? does the pedal ever sink? more info!

brake-booster??

if its the brake booster.... it'll feel like there is TONS of pedal like it hard to push cause the brake booster is a power option...... just like power steering....


bleed the lines, adjust the rear drums, lube up all your sliders on the front and if that doesnt help its time to rip off the master cylinder

master is shot

or you could have a leaky wheel cylinder

a leaky booster will give you a soft and sinking pedal similar to a shot master

actually it will give you both. I've seen more bad check valves or bad boosters give a more hard pedal then a soft pedal. Never replaced one on a honda though, so not sure what would be the common failure. But I do know that master cylinders fail alot on our cars.

i just rechecked the wheel cylinders lubed all slider and checked the lines from the master to all 4 wheels. everythings clean and solid. i'm gonna see if i have a spare master lying around maybe swap it out see if that helps.........thanks for all your info.....

just pump up the pedal a few times untill it gets really hard. Hold it firm for 30 seconds.. see if it drops at all. If you do.. you got a leak. If you said all the lines and w/c's are good then change up the MC.