I changed all brake pads on 2007 Aspen. I started on the front left, and used a technique I have seen and heard about when collapsing the caliper pistons. After I applied the c-clamp, I opened the bleeder screw and continued to apply pressure with the c-clamp. I don't remember if I used the bleed "open" to drive the pistons all the way open or just pushed the pistons open enough to remove the caliper and then pushed the pistons all the way open with the bleeder closed and pushed the fluid back up into the system. That was the only wheel I did that to. The other 3 i just pushed the fluid up into the system, the traditional way.

After I replaced all the pads, I had no brake pedal pressure. I thought I might have gotten some air in the front left line somehow. So I started bleeding. I would get a pedal throw or two of good fluid and then a lot of air. Not just bubbles, but big "bullets" of air. If I pumped fast, the fluid mixes with air and becomes almost frothy. On occasion when I would get good fluid, I would hold the pedal all the way down and noticed bubbles of air would start coming into the line. Additionally, I have been able to pump up a little pedal pressure once or twice, but it soon went away. After more than a quart of fluid being pushed thru the left front caliper, I still don't have normal brakes. I have considered a new caliper, but really don't think that's the problem and am down to calling the tow truck of shame and (gasp) having a garage unscrew my brake job.

Any suggestions?

 

Sounds to me as though you are not bleeding the system correctly!? When bleeding, you don't pump the peddle, a helper will just open the bleed screw as you press and hold the peddle down and then the helper closes the bleed screw after air and fluid spirts out, then let the peddle back up. Then again press down on the peddle while someone (helper) loosens the bleed screw again... the peddle will float to the floor slowly. Hold it down again till the helper closes the bleed valve. Perhaps you are doing it this way.. Just trying to assist..

 

should have never opened up the bleeder screws U have air in the line simple as that.

Fill master cyl up to top with fluid.
2 people for this job pump up brake pedal 3x then hold it to the floor.
Start right rear brake and bleed until no air bubbles.
Repeat for all wheels Make sure fluid is full in master cyl half way through.

 

I have tried every method possible to bleed this line, including the one mentioned. Also, I have one of those one-man bleeder bottles that allows me to make multiple pedal pumps until the little bottle gets full. Obviously, to no avail.

I know lots of people who have used the bleeder open technique to get the caliper pistons open. Additionally, I see it on the Internet (including NAPA How To videos) showing guys doing it that way. in my mind, opening the bleeder at the bottom of a pedal stroke during bleeding procedure is no different than applying pressure to the piston with a c-clamp and then opening the bleeder screw. You are pushing fluid of the bleeder hole either way. I didn't back off the c-clamp with the bleeder open. I had to push the pistons open while the caliper was still on car because the rotor was worn and had a ridge around the outter edge, preventing me from just pulling the caliper off.

Chrysler Tech, now that you have properly scolded me, how do you recommend I get the air out? Did I get air in the ABS? If so, what do you do about that? Or, do I try a pressure bleeder that pushes fluid in at the bleeder screw and push air back? I have only been trying to bleed the left front line. Do I need to start at back right and work my way around?

Thanks

 

A the ABS is electrical not mechanical no need to mess with it get thet out of your head.

B "I have only been trying to bleed the left front line. Do I need to start at back right and work my way around?" This is the second issue

Re read in my post what I asked you to do. In 17 years of doing brakes I have never once opened up any bleeder valve you only cause issues like introducing air into the system when you do this.

Reread what I said in the post above all of it.

 

I didn't see your original instructions in your first post. I'll go give it a try.

Thanks

 

Well I have followed the above procedure to no avail. both front calipers act the same. Lots of air, very little fluid. Back wheels are fine.

It seems that there is air in the master cylinder. If I loosen the aft fitting at the master cylinder ( there are two fittings. I am referencing the back fitting closest to fire wall) while brake pedal is depressed, a little bit of air comes out. The front fitting puts out only fluid when following the same procedure. The aft line seems to feed the front part of a box/valve (ABS?) while the front line feeds the back part of the box. From there, the incividual brake lines go to each caliper. The front part of the box has in proximity the individual lines to the front calipers.

I am wondering if the back part of the master cylinder is bad. Would that also account for lack of brake pedal pressure? although that doesn't make sense. Why would that be bad now.

Thanks

 

The master cylinder has 2 chambers and a sliding piston. Make sure you keep enough brake fluid in the master cylinder while attempting to bleed all brakes or you could just be sucking more air into the system through the master cylinder port! Gotta keep the fluid up near the top and keep checking between pumping the peddle. Believe me the fluid level goes down fast in the master cylinder and if it gets down to the sliding piston port it will take in more air!

 

How to Bleed Your Brakes - For Dummies