Brake Issues (again)

[jmartin99]

So, a couple months ago I completed a TOTAL brake system replacement...EVERYTHING was replaced. Master cylinder, power booster, proportioning valve, lines both hard and rubber, calipers and wheel cylinders. Now, I attempt to bleed the front calipers after my daughter telling me her Jeep pulls to the left on braking and I get ZERO fluid out of the right caliper. I get fluid with no issues out of the left caliper. I have a union in the line going to the right caliper so I unscrew one side of that connection and still have no fluid there. I unscrew the line from the back of the proportioning valve and I get a little fluid from there.

If the piston inside the proportioning valve has moved to block the front brakes because it sensed a loss in pressure, wouldn't it prevent fluid from coming out of BOTH front calipers?

I have a good strong brake pedal...

Without removing the proportioning valve, I unscrewed the brake light switch from it and it appears to me the piston is not centered and is possibly moved toward the firewall, which would block the front brake fluid supply. I stomped on the brake pedal a few times to attempt to re-center the piston but it did not appear to move. Any suggestions on how to get the piston back centered? I ordered the tool to keep it in the center while bleeding provided I can get it back in the center.

Thanks!
Jeff

 

[mrblaine]

So, a couple months ago I completed a TOTAL brake system replacement...EVERYTHING was replaced. Master cylinder, power booster, proportioning valve, lines both hard and rubber, calipers and wheel cylinders. Now, I attempt to bleed the front calipers after my daughter telling me her Jeep pulls to the left on braking and I get ZERO fluid out of the right caliper. I get fluid with no issues out of the left caliper. I have a union in the line going to the right caliper so I unscrew one side of that connection and still have no fluid there. I unscrew the line from the back of the proportioning valve and I get a little fluid from there.

If the piston inside the proportioning valve has moved to block the front brakes because it sensed a loss in pressure, wouldn't it prevent fluid from coming out of BOTH front calipers?

I have a good strong brake pedal...

Without removing the proportioning valve, I unscrewed the brake light switch from it and it appears to me the piston is not centered and is possibly moved toward the firewall, which would block the front brake fluid supply. I stomped on the brake pedal a few times to attempt to re-center the piston but it did not appear to move. Any suggestions on how to get the piston back centered? I ordered the tool to keep it in the center while bleeding provided I can get it back in the center.

Thanks!
Jeff

If it is that stuck, you may have to remove the port behind it and push it back forward to center it. Explain the lines to the front better. In stock form without ABS, there are two lines to the front. Why is there a union?

 

[jmartin99]

When I replaced the hard lines, I ordered pre bent lines from Rock Auto. The front right line was going to be impossible to install without removing LOTS of stuff so I opted to use 2 generic lines from Autozone and used a union to join them centered under the front cross member. I did use an inverted flare union to join them.

 

[jmartin99]

So, when I went out to attempt to get the brakes bled again yesterday...
I unscrewed the brake light switch from the proportioning valve and used a small screwdriver tip and appeared to get the piston centered. I screwed the brake switch back in to hopefully hold the piston in the center. I then had bought a new oil can and a foot of clear 3/16" poly flexible hose. I put the hose on the oil can where the flexible hose that came with the can screws on. I filled the oil can up with brake fluid and connected the hose to the bleeder screw. I slowly pumped the oil can and pushed the fluid into the caliper and through the lines. My daughter watched the master cylinder and said she saw bubbles coming up at first then the fluid started to raise. After reaching the full mark on the master cylinder, I closed the bleeder screw then went to the left side and bled the left caliper a couple times, getting air bubbles the first couple times then just solid fluid. I then tested the brakes and took it on a test drive and the brakes are working good again!
I am not sure what happened previously to make the right side caliper quit working but hopefully it is fixed now and will work good for a long time! LOL