Brake troubles

On my 03 2.7l my brakes feel like they have air in the line and I have blead a whole bottle through the master cylinder. I pulled the master cylinder out of the brake booster seals were good no leaky, checked the lines down to the calipers down the frame to the rear drums no Leaky pulled the drums off rear wheel cylinders were not leaking but 12 years old it appeared so I relolaced them blead the hell out of front and rear its got all new fluid in it with no bubbles or foam just clean fluid ... Now the cool part .... Brake goes 3/4 way to the floor it works and will stop the truck but pissed me off and still sometimes feels like there is air when I stop kinda like my abs is working but I'm slowly pressing down on the petal not locking the brakes up on ice ... I've pumped them like crazy when bleeding can't build up a lot of pressure I know it's the story of a leak but I've look everywhere has anyone had this before ?

 

How are you diagnosing air in the line? Air in the line typically results in ineffective braking as part of your pedal travel gets used to compress the air instead of pushing brake fluid. If it's air you should be able to quickly pump the brake pedal and get your braking back and firm up the pedal.

 

When the truck is not running I can pump the pedal and it will get firm but when I crank the truck it won't get firm and goes down 3/4 to the floor

 

I'm real tempted to say you've got a leak. It sounds like you've checked all the external possibilities. I'm going to guess the master cylinder is leaking internally, or maybe the ABS pump. Does it have ABS?

 

Yes and it threw a code for abs Sensor they are 300$ each I erased the codes I scanned it after 200+ miles with no codes ... The master cylinder I pulled out of the brake booster the seal on it didn't appear to be bad there was no fluid ... Could it still be messed up and not workin properly giving me the spongy pedal ?

 

If there are no visible leaks then it reads like you still have a air bubble trapped.

The rear load sensing proportioning valve was bled also?

Hand pump pressure bleeders that strap to the master cylinder are a wonderful thing. I bought a multi fit kit years ago from Jegs and have used it many times for bleeding and flushing new fresh fluid thru out the system. It's a quick, one man show, to get a ugly job done.

Some guys like the cheap vaccum hand pump to pull fluid thru the system. I was spoiled by the pressure bleeder because it's so fast, easy and it can't miss(or it hasn't yet).

 

You got a link to that? I've been using the vacuum type and am really not that happy with it.

I'm going to disagree with the air bubble, though. Without a leak an air bubble won't spontaneously appear. However, a seal going bad on a master cylinder piston will.

 

I never blead the load sensing pro portioning bypass valve guess I'll try that is it the same as caliper and wheel cylinder pump the brake and hold pressure then crck the valve ?

 

This is the one I bought.
http://www.jegs.com/i/Motive+Products/715/0250/10002/-1


The rear prop valve should be bled,,then your rear wheel cylinders, in that order.

Yes, it gets bled the same way,,just don't have a heavy load in the truck to where it is squatting down visibly in the back. You could cover some of the port holes in the valve and could trap air between. Mine goes up on jack stands on the rear frame when that is bled (axle and suspension hanging). Probably overkill, but it's what I do when I bleed the systems.

Edit: just seen the abs code post, and you might be having issues with that then.

 

What he said, minus the jegs bleeder, and only cause i dont have one. I would say its the mc IF it still feels/acts wonky after you bleed the bypass valve..

 

Yeah man bled the bypass valve had clean fluid in it no foam or bubble along with the drums an calipers .. I'm gonna do the master cylinder it's the same one from 03 hopefully that's it

 

Just read through the fsm, cause i am having somewhat of the same issues. Fsm is for an 03 taco. Try adjusting the rear brakes first, its a darn site cheaper... http://web.archive.org/web/20080731033603/http://www.ncttora.com/fsm/