my brake pedal is doing some weird stuff. for the past couple of weeks when you hit the brakes and the pedal is soft, pump it once and it feels normal, and if you pump it again it'll go back to being soft. still brakes fine, just takes a little bit longer to come to a complete stop.

but earlier today....

i was leaving a parking lot, and in a turn lane. there was a car about 2 or 3 car lengths infront of me, i pressed the brake pedal, it went straight to the floor and nothing happened. so i turned hard left, went over the median, mowed down some trees and made a u-turn back into the parking lot. i popped the hood, got out, checked the brake fluid, and the master was full. so i jumped back in the truck hit the brakes and it was back to the usual soft then normal pedal.

ever since that happened it takes ALOT longer to come to a complete stop. and the pedal went straight to the floor 2 more times on my way home.

i've been driving real slow, engine braking when i can, and using the hand brake along with the pedal to slow down. that got real old real quick.

so what do you guys think? master cylinder? brake booster? what's the best way to check either one.

and like i said the master has plenty of fluid in it, and i don't see anywhere on the truck where fluid has been leaking.

 

I vote master.

 

Mine acted like that when my master cylinder died - but I needed rear drums and a LSPV too.

 

Mine is doing the same thing. I'm pretty sure it's the master although I haven't replaced it yet so I can't say for sure. I'd say if the engine is off and you step on the peddle and the peddle eventually goes to the floor, it's the master(mine does).

 

my brake pedal is doing some weird stuff. for the past couple of weeks when you hit the brakes and the pedal is soft, pump it once and it feels normal, and if you pump it again it'll go back to being soft. still brakes fine, just takes a little bit longer to come to a complete stop.

but earlier today....

i was leaving a parking lot, and in a turn lane. there was a car about 2 or 3 car lengths infront of me, i pressed the brake pedal, it went straight to the floor and nothing happened. so i turned hard left, went over the median, mowed down some trees and made a u-turn back into the parking lot. i popped the hood, got out, checked the brake fluid, and the master was full. so i jumped back in the truck hit the brakes and it was back to the usual soft then normal pedal.

ever since that happened it takes ALOT longer to come to a complete stop. and the pedal went straight to the floor 2 more times on my way home.

i've been driving real slow, engine braking when i can, and using the hand brake along with the pedal to slow down. that got real old real quick.

so what do you guys think? master cylinder? brake booster? what's the best way to check either one.

and like i said the master has plenty of fluid in it, and i don't see anywhere on the truck where fluid has been leaking.

 

Could be air in the lines or a master cylinder. A bad booster wouldn't cause the pedal to go to the floor. With the engine off, pump the brake pedal a couple of times to get rid of the booster vacuum. Push hard and steady on the pedal and it shouldn't move much at all from the full out position. If you can push it more than an inch or two or it slowly goes to the floor you most likely have a bad master. If you have a leak at a wheel or a pipe connection air could get into the system but that would also cause a fluid leak that would cause the reservoir to go down. Look for leaks and try bleeding the wheel cylinders and calipers first, and then replace the master if the problem continues.

 

thanks guys!

sorry about double posting the thread, my internet was acting up earlier. it was taking forever to load to i hit "submit post" a couple of times

 

mod please lock, double post sorry

 

subscribed, mine does the same thing!! hasn't hit the floor yet though, although it will scare me when it catches me off guard.

 

today i double checked everything for leaks. found nothing. so i put a new master cylinder in and it's fixed.

the truck stops in half the distance it's been taking in the past couple of months. i guess the master was on it's way out for a little while now.

 

lol... that can happen.

some tips:
Constant pressure on the brake pedal and pedal slowly sinks to the floor: bad master cylinder
Pumping brake pedal increases braking force: bad rear wheel cylinder(s) or bad master cylinder or air in the master cylinder or brakes need blead.

 

yeah, i had both wheel cylinders go out in my s10, and i had similiar problems with the pedal, but i had to top off the brake fluid atleast once a week. with the 'yota it never leaked any fluid.

one time in the s10 i was going downhill from the bridge going to work, the light at the foot of the bridge turned red and my pedal went straight to the floor. i managed to stop before rearending the car infront of me though. i HATE when brakes don't work