2002 3.0 2WD Automatic, 200k miles

Hey everyone, here's an issue I've been chasing since this spring.

Earlier this year I put on new brake rotors and pads. Rotors weren't compatible with wheel sensors and it would throw an ABS light. I didn't know it was the rotors so I tried bleeding ABS and all the wheels. Ever since that day, my brakes have been soft/spongey (don't know if it was caused by the rotors or the brake bleeding)

Fast forward, I ended up figuring out the rotors were causing the light. I had my OE rotors resurfaced on a lathe and put them back on the truck. Brakes are soft so I figured it must be Master Cylinder. Replaced master cylinder and bled brakes again. Brakes are still soft!

Overall, I've flushed the brakes MULTIPLE times, replaced master cylinder, bled ABS, my brakes are good, my rotors are good, I don't leak fluid so I doubt I have a bad line.

What else could be causing the soft brakes?

Thanks!

 

Soft brakes means one of the lines or caliper/slave needs extra fluid, or there is air in the line that is being compressed by fluid pressure
Brake fluid doesn't compress much at the pressure used, air does and quite a bit

You seem to be focusing on the front, rear can be cause of soft pedal as well, master sends out about the same pressure to all 4 wheels, rear get a little less
So front or rear can cause same soft pedal issue

Hold out the E-brake release and pump the e-brake pedal several times, this activates the e-brake self adjuster to tighten up e-brake in both rear wheels, can't be over tightened

Press brake pedal down now, if it goes lower then that means they were out of adjustment
Try braking now

Gravity bleeding
Remove cap on master
Open right rear wheel bleeder, farthest from master, let it gravity bleed for 30 seconds or so, should be a nice steady flow with no air bubbles, if you see bubbles then let it bleed longer until bubble free
Do same on left rear, then right front and left front

Fluid is free to flow from master to all 4 wheels when brake pedal is up, no closed valves inbetween
Top up master
Try brakes again

ABS light won't cause soft pedal unless the ABS module itself is the problem, light just means don't count on ABS working in a sudden stop

 

Thanks Ron, I'll give that a try and update the thread

 

Just tried the e-brake method. Brake pedal sinks lower now. Does that mean I just need to re-bleed all 4 brakes or is there something else I need to do?

 

Bleed rear only then retest

Reads like one of the slaves(wheel cylinders) is needing too much fluid

Calipers and slaves need more fluid inside as pads and shoes wear down, so after braking less fluid returns to master, it stays in the caliper or slave, minuscule amount but not 0

So long pedal travel means something needs more fluid to expand it