2005 trailblazer - 80k miles. Recently bought and have been going through changing all the fluids as only the oil has ever been changed. Did the transfer case and both diffs which went fine. then it was time for the brakes. I read that gravity bleeding was the safest and easiest so I went with that being my first time. I hook a clear hose to the bleeders and ran into a bottle. I cracked them and let them trickle out. I was refilling and the MC NEVER went even close to empty. I ran each one until fluid was clearish. I made a big mess when the hose kept pulling off the bleeders but otherwise seemed to go fine.
Until I went to drive it and found I could push the pedal to the floor. I took this to mean I had introduced air into the system. But searching online came up inconclusive as to whether it’s normal (on some cars) to be able to push the pedal to the floor if you try. It doesn’t need to go anywhere near the floor to stop. In fact, it’s very responsive and firm up top. I only have to press a little bit to stop the car. And if I hold it there, the pedal stays without dropping. But if I put anymore pressure to it, it’ll go to the floor without much effort. Doesn’t sink at traffic lights. When engine is off, it takes 2-3 short pumps and then gets rock hard. turning on ignition makes it drop a little and it does have pressure but if I push, it’ll go to the floor. the biggest issue I think is that I can’t pump up the brakes when ignition is on (not that I’ve needed to). I pump and pump and I can feel it gain a little hardness and then that goes away and it’ll sink from the pressure I was putting on it when it was hard. this is the only time it “sinks”. Before bleeding brakes, the pedal was inconsistent. At times it felt ok and at other times it felt kind of mushy. I mostly didn’t like the inconsistency and the fact it was 15 year old brake fluid. I don’t know if I could push the pedal to the floor but never noticed that I could.
I just replaced all 4 pads a few hundred miles ago. Rotors looked ok. No vibration, no noise, no pulling and I used a IR gun to check temp on all 4 rotors for a few days after the change and they all were the same as before the pad change (and both sides matched each other for front and rear).
So I thought maybe I managed to screw up the easiest and safest bleed method and bought a vacuum pump set. What a POS. It holds vacuum but I can’t get it to pull anything but air and a few drops of fluid when cracked. None of the included fittings work and I tried zip tying but that only helped a little.
My other thought is the master cylinder but shouldn’t it be sinking instead of holding pressure a stop lights?