My brake pedal goes nearly to the floor when I step on it... but the brakes still work fine and the fluid level is fine. I'm unable to pump them up also, like you could if it was just air in the lines...

is this a bad brake booster?

(if i hit the brake quickly, like in a panic stop, there's pedal pressure just briefly....pressing the brake normally sends it almost to the floor before it applies the brakes. there's no fade once you get to that point.).

 

I had to back off the adjusters in the rear drums of my truck to get it to my mechanic because my drums were filled with grease and sticking. (axle seals) The truck did the same thing as you are mentioning. It could be air in the lines. Maybe try and bleed them?

 

Why would air be in the lines if you have not worked on your brakes and you are not leaking fluid?

Only 2 things left if you have not worked on them and fluid is fine, booster aint boosting or MC has gone kaput.

Lots of places do free brake inspections then fix yourself.

 

I wouldn't condemn the booster with the pedal going to the floor. Sounds like the MC is by-passing internally to me.

 

Sounds like a bad MC to me......


Did this just happen all the sudden or were you doing work on the brakes?

 

Sure, it could be that exactly, a bad MC, but this is diagnosis by internet without the benefit of physically testing the brakes myself for symptoms, so I offered a process of elimination not a process of condemnation.

Like I said, lots of places do FREE brake inspections in hopes you will let them do the work.

 

My friends dad has an 85 pickup and he has the same problem, he bled the brakes 3times and still no brakes. then he bouht a new MC and it still didnt work. well it ended up the the new MC he bought was bad. and he bought it brand new.. go figure. Id bet on the MC

 

Honestly, Yota brakes are crazy, i don't get them, they just do weird things. I had air in my system after bleeding them three seperate times, but wasn't loosing fluid and then, i messed around with some random stuff, took off some various lines, decided to bleed the LSPV and viola, i have pedal again. In this case though, it seems like the Master Cylinder could be the culprit. First step would be to see if there is air in the lines. Bleed the brakes and if you have pedal for a couple uses, maybe a couple miles, then you might have a bleeder or something that is rusted/worn and is leaking air not fluid, i've run across that twice now. BUT, if you still don't have any pedal after you bleed the brakes, i'd say your master is dieing.

 

Usually a bad booster will hiss audibly when you press the brake pedal down, sounds like a bad MC to me to.

 

how does the brake pedal feel with the engine off? The pedal will be harder than if the engine is running because of no brake assist, but if the pedal still feels soft I'd go with the master cylinder

 

good responses.

my brother's 88 4runner had the same bad MC problem as described above. replaced it with a new one that was bad....


one other note, (actually 2), I did notice that the fluid in the resevoir is nasty....cloudy. and I noticed a tiny bit of paint stripping on the front of the booster like the rear MC seal might be leaking....

 

these new MCs that were installed....were they toyota? or some vatozone junk?

I would recommend NOT compromising on your brake system...for dee safety reasons

 

what do you think?

 

you know, i just thought about that to, i once had horrible pedal because my drums were so far out of adjustment, so that might be part of the probelm as well.

 

Who ME?

I try to avoid thinking as much as possible

 

half the time people replace their master cylinder and think it is bad because they did not bleed the new one properly and take it back for another one.

http://www.denlorstools.com/home/dt1...h_article.html

contamination in your brake fluid would not be a good thing.

take the truck somewhere for a free estimate as recommend before. Find out what is wrong and then go from there.

 

If the paint is shrivelled up on the booster like you say, the MC is FOR SURE leaking. Replace it and your problems will go away.

 

I would say that, aside from air in the lines, this is the #1 cause of brake pedal issues. The adjustment of the rear brakes greatly affects the feel of the pedal - that's why there is an auto-adjuster in there.

 

lol, auto-freezers maybe....

 

Hey, I didn't say they work . I have seen about 2 autoadjusters that actually work properly.