I removed my right front caliper from the rotor, inspected the brake pads and went to go put it back on, I noticed a slight weeping of fluid from one of the pistons. I haven't driven the car much this year. so while slowly pushing the pistons back in to get enough room to slide over the rotor, I must've pushed a tad crooked which slightly moved one piston to one side. I corrected the piston but I must've pushed air back into the system. Because when I put it all back together and started the car I had no brakes, and the light came on in the dash. I drove it around my neighbor hood but nothing changed. So I ordered a new caliper. When I removed the old caliper I noticed not a drop of fluid leaked from the line. While the car was up on stands I changed he passenger rear caliper out as I had one already. I was going to change that one a couple years ago when that one weeped but it stopped weeping. Anyway so now I have two new calipers on the passenger side. I gravity bled the rear, but when I tried the front still no fluid. I capped the master, tightened the bleeder and pumped the brakes ( I was alone ) just trying to get something to push some fluid to the right caliper. Again nothing. I tapped on the caliper and everything. So I thought maybe I should tap the proportioning valve, so I did, then went back and tapped the caliper again. pumped the brakes, un capped the master filled the fluid, I did noticed it did drop just a tad. cracked the bleeder still nothing. So I left it open with the clear hose attached into my bottle, went into the house for a while. When I came out the fluid was flowing, the front chamber of the master was half empty and the caliper line was dripping well. I tightened the bleeder, put the rest of my fluid I had in and capped the master. I need more fluid so I'll finish it tonight because I still noticed some air in the line, tiny bubbles but still.

Long way to my questions, but I want to ask those who may have much better experience, did tapping the proportioning valve have anything to do with my success in getting fluid to flow? if so does that mean I should replace it? Also should i continue to gravity bleed all 4 wheels or should I invest in one of those systems that force pressure through the master cylinder? Pumping the pedal has never worked for me.

 

After you bled the right rear with the new caliper, you said you moved to the right front and got no fluid. How long did you wait for fluid to come out when you say 'still no fluid'? Gravity wise, it can take some time. As far as should you get some power bleeding apparatus, totally up to you of course, but if you aren't in a hurry then gravity will work. And as for tapping the proportioning valve, I would think that barring any leaks in the threads of the lines to/from that valve, I would guess the only way air would get that far is if the front master cylinder drained completely and down thru that valve. Just my guess.

 

Yes, I gave it about 30 minutes with no activity. Once I tapped the valve it flowed in about 10 minutes. I've done many of brakes in my day and never had an issue where I lost brakes just by pushing fluid back into the master, I still feel I pushed air back into the system through that leaking piston. I'll keep gravity bleeding, I've got plenty of time.

 

I gravity bled the systems last night. waited about 2 min. each valve. had fluid out of each one. I got the most air out of the front passenger caliper, I even tapped the prop valve and more air came out. When I thought I had it all, I tightened all valves, capped the maste rcylinder and then pumped the brakes. The pedal felt firm, until I started the car. At first the brake light was still on, after pumping the pedal slowly it soon went off, but now the pedal feels soft again and will go almost to the floor.

Now what do I tackle? I really am not sure which way to go to solve this soft pedal issue. Could it be the booster?

 

Sounds like you still have air in the sytem.
Invest in a Motive Bleeder or use one of these to center the combination while bleeding manually...

 

As a follow up, I gravity bled the brakes one more time with special attention to the passenger front, tapping the prop valve as that caliper bled. I have a pretty good pedal. I want to replace my rear rubber lines this fall or winter and when I do that I might just invest in the motive bleeder, I could not find one locally so I will plan for that change out. when I do I will replace all the lines in the rear with new lines.

Thanks for the replies I can get some well needed driving in before the end of the season.

 

I've got a pair of new rear rubber lines that I don't need. AC Delco Premium 18J91 GM 19173076
If you want them I'll sell them for $20 shipped.

 

Thanks for the offer, I'm not sure if there is any difference between the AC Delco and NAPA, but I already have Rubber lines from NAPA. What I need to buy are the steel lines. Actually I might even do the SS lines.