okey that is wierd. to have somthing working just to stop. there could be a leak which your not seeing. Did you check the piston, there is a square lathe cut seal which is supposed to retract the pistons that you might be not seeing. what i ment was if you changed the calipers and put the left on the right side was supposed to go ect.

 

i have seen at work that brake fluid has gone past the seal causing a low pedal

 

I havent touched the calipers yet except for bleeding them. I really doubt they are leaking since when I bleed them I am not getting any air out of them and my system is not loosing any fluid but I will check them in the morning anyway just in case.

 

i know that it's not by the book but i would would vice grip the flex hoses one at a time to help elimanate where the problem is

 

That's not a bad idea, I'll try that in the morning too. Thanks and if you come up with any other thoughts please let me know because I am stuck...

 

I don't want to speak too soon but I think I fixed them! I recently put a new wheel bearing in and never tightened it again after installing it and driving it. So, over time it became loose again and was causing the wheel to wobble which was pressing in the pads against the caliper pistons making it so when the first time I stepped on the peddle it would go to the floor after driving a while. This is why when I had the truck in the garage I would step on the peddle and have brakes, but after driving for a moment I wouldnt unless I pumped it. I hope this thread helps someone else. Thanks everyone.

 

did you open all 5 valves??? on these toyotas there is 2 valves in the front and 3 in the back. the 3rd one is in the middle between the back 2 brakes. i didnt figure that out for a long time so just a heads up if you didn't know that.

 

Glad you figured it out man best of luck!

 

good job man, i knew the rotor was somehow pushing the pads back lol. kinda sucks that you went through bassicly the whole brake system including 3 masters.

 

I don't want to speak too soon but I think I fixed them! I recently put a new wheel bearing in and never tightened it again after installing it and driving it. So, over time it became loose again and was causing the wheel to wobble which was pressing in the pads against the caliper pistons making it so when the first time I stepped on the peddle it would go to the floor after driving a while. This is why when I had the truck in the garage I would step on the peddle and have brakes, but after driving for a moment I wouldnt unless I pumped it. I hope this thread helps someone else. Thanks everyone.

Alpha,

Did this end up solving your problem? I am having the exact same problem and am glad I found your post. I pulled into work the other day and about ran into a co-workers car. Scared the crap out of me! I have replaced the brake booster, both wheel cylinders and the MC twice with no luck. On top of bleeding the back brakes and MC multiple times. However, I have not checked the wheel bearing or pads. I will hopefully get a chance tomorrow. I really hope that solves the problem. It has been driving me crazy. Anyways, thanks for your post. I hope it solves my problem also.

 

Yep sounded like he fixed to me too.

Warped rotors is the normal cause for pushing the pads out. You can have wheel bearing play and it not cause this issue too.

I always pump just to make sure they're there long before I need to get on them hard.

It only takes brake failure once in the http://en.wikipedia.org/wiki/Guadalupe_Peak to get you in this habit. Pure clincher that one is with brake failure!

 

You would think a loose wheel bearing would also cause some other issues as well .

Now maybe the front wheels were never off the ground but Old habits die hard and I always check the front suspension when ever I have the front wheels off the ground.

With having redone brakes on these vehicles till I dream about it.

I have never bleed a master Cylinder and only attempted a LSPV once that was a very expensive lesson. Then I do use a Vacuum brake bleeder.

 

Yes, the loose wheel bearing was my problem, I just cranked down on the (I think 36mm) nuts and it's been fine ever since. Jack the truck up and see if you can shake the wheels. If they have some play tighten it. However, considering how old our trucks are, and how Toyota made a design flaw running our brake lines in between the gas tank and the frame- I would highly recommend for everyone to change those rusty rotted out lines because one day they will burst.