96LT1AUTO

Good morning all,

I checked my brake booster by giving a few light pushes on pedal and holding while car was off. Upon starting the pedal fell approximately an inch or so. Not sure if that was enough to indicate that booster is okay but enough for me to question a couple things.
First did opening the bleeders all the way during bleed out possibly allow air to be sucked back in if my helper prematurely released pedal?
Second, since I have ABS did I use correct bleed sequence that is normally used? I watched a YouTube video where the mechanic explained with an ABS motor the bleeding sequence/procedure is different.
Third, did I lose vacuum to the booster? Is that connection/check valve between vacuum from motor and booster itself bad?
I am going to start by doing another brake system bleed but I need some more info about bleeding an ABS system.
Vettes Rule

belairbrian

I'll be doing the brakes on my 92 soon so I've been reading up on the process. The FSM has a couple of things I hadn't seen before.

I was taught to "pump up the brakes" before opening the bleeder. The FSM states slowly depress ONE time and hold.

After closing the bleeder, release pedal and wait 15 seconds before depressing again.

Other stuff was pretty normal.
Deplete all vacuum in booster before starting the bleed process.
Sequence of RR, LR, RF, LF was like I've always done.
Attach tube and keep open end submerged.

If the pedal is released early it can certainly pull air in. Especially on the first couple of cycles. I think the 15 seconds between cycles is there to address this. The FSM doesn't state a length, but I like the vertical rise from caliper to the arch in the tube to be at lest 12 inches. This, along with waiting, allows any air bubbles to rise too high to be pulled back. That is how long I wait, until all air bubbles have reached the arc in the tubing.

Nowhere Man

I think you need to hook up a scanner and run the ABS pump

96LT1AUTO

Ok using scanner was something I overlooked. Rookie move. I also will substitute pumping multiple times with FSM recommended 1 slow pump the open bleeder with a verticle rise on tubing. Thx

c4cruiser

If you really wat to make the bleed process simple and a one-man procedure, get a set of "Speed Bleeders" and install them in place of the stock bleed valves.

The Speed Bleeders have an internal check ball with a spring that closes the ball once brake pressure is released during the bleed process. They also have a thread sealant so that you can open and close the bleeders many times and not worry about air getting past the threads.

All you have to do is to connect a rubber tube over the end of the bleeder, open the bleeder about 1/2 turn and then simply press the brake pedal down and then release it. Once you see fresh fluid coming out, close the bleeder and move to the next caliper.

aklim

Motive Products makes a brake bleeder. Dump the fluid in the reservoir and put fresh fluid to the rim. Hook this thing up and pour fluid into the tank. Pressurize to 15 psi. Open the bleeder till you are happy. It won't run out.

Obviously you will have to have a scanner if you want to pulse the ABS.

Best part? Makes brake flushes so easy you can buy adapters for other cars and do them every couple of years.

96LT1AUTO

It looks like I have much more info/avenues to explore without getting into booster..ugh..Ok here's my plan. Put her on stands, pick up a scanner, inspect previously installed parts, change to speed bleeds or to other bleeder pump with 15 psi. I think another bleeding should bring success. Then it's back to thx all!!