Brake booster or air bubbles?

Hey guys,
I recently posted something similar but I had a seized passenger side caliper so I had the shop replace both calipers, the rotors, and new pads. When I got my truck back I noticed that not only does the truck have less stopping power than before but I still have the same old spongy brake pedal. I tested the brake booster by pumping the brakes while the car is off and turning the ignition to see if the brake pedal depresses upon ignition. It did. I'm wondering if you think that maybe the brake master cylinder is leaking and that's why it's spongy? Maybe air bubbles in the lines. I got powerstop rotors and brake pads and some new calipers from O'Reilly's. The brake pedal does not go all the way to the floor when I'm braking but it does take quite some effort before the pads start catching on the rotors. When I pumped up the brakes with the car off, it built up quite a lot of vacuum/pressure which is why it doesn't seem to me that the brake booster is failing? Thanks!

 

You still have air in the lines or that got into the ABS module. The shop needs to follow the proper brake bleeding procedure to get it out.

Brake boosters don't build pressure when the car is off or work in that manner you are compressing the fluid in the lines to build up that pressure on the pedal when the car is off.

 

Okay. I'll talk to them. Air bubbles can make it that spongy?

 

Yes air in the system can cause a spongy pedal.

 

I took it back to the shop. They drove it and said my back drums just need an adjustment. The drums and shoes are original.

 

I had to take mine into to a Toyota dealership that had a brake flushing machine to finally get back a decent pedal, this happens quite often if you search Spongey brakes you can read thru many threads on it with really little explanation on why this happens, I changed out my brake pads without opening the bleeder valves which may have caused it but im not quite sure.

 

Almost positive they didn't bleed the system properly.

 

You don't think I just need to drums? If they didn't bleed them properly, they're clearly not admitting to it. What is the difference between improper and proper bleeding?

 

The sequence in which they did them and the procedure used.

 

Improper just means there is still some air in the system. I just did mine Saturday and after gravity and vacuum bleeding them, I had the same symptoms as you. Softer pedal than before. It was easily remedied with conventional bleeding. A buddy pumps up the brakes and holds and presses the pedal down (and doesn't let it come back up), then you loosen the 10mm bleeder screw forcing the trapped air out. You then tighten the bleeder screw, he pumps again and holds, and repeat a few times then do the other caliper. Our (really big) 4 piston calipers have plenty of room for air pockets to hide. Very often (but not always) after bleeding one must re-bleed them after driving a bit. This allows any trapped air to be dislodged. It only takes a vey small amount of air to create a soft pedal. The rears are separate in our Tacomas so unless they cracked open the rear section, it sounds like they just need to re bleed. Keep in mind that the fronts do 80% of the braking. If your rears completely failed, you may not even notice it. But all in all, yes, it sounds like they are shirking responsibility for a poor bleeding job.