Technical Strange Brake Proble

Today, I replaced the front calipers on my Buick and one of the hoses. (The other hose was new and was replaced before I bought it.) Before I disconnected the brake lines, I put some stroke on the pedal with a 2X4 wedged between the pedal and seat to keep the fluid from draining from the reservoir.

The reservoir and master cylinder are under the car, not on the firewall. It does have a vacuum booster that was also working well. The only problem I had was a sticky left front caliper.

Before I worked on it, I had a great pedal. Now, after lots of bleeding, I have a pedal that's like stepping on a marshmallow. What happened? I did leave the hoses disconnected for a couple of hours. I've done lots of brake jobs and never had this problem before. Could it be that air bubbles traveled up the line to the proportioning valve? The hose was higher than the reservoir.

How should I approach this?

 

We changed calipers on a Mercedes years ago, and switched them side for side. That put the bleeders down, and we could not get them to bleed, until we put them on the correct sides.

 

Nope. Bleeders are right side up.

 

pressure bleed? do you have access to a pressure bleeded?

 

First I'd back bleed the calipers. Take them off the disk and stick a shim between the pads thick enough to prevent the pistons from blowing out, then pump the caliper up with the pedal.

Now go press the pistons back in all the way & fluid plus air will be forced back to the master cyl where air will expel from the cap vent.

Repeat until the air excapes.

 

It would be really hard to get a pressure bleeder on the MC. There is just enough room to get the cover on and off.

May as well try pumping up and back bleeding the calipers. Hadn't tried that one yet. Tomorrow.

 

I always have this issue on my bike because there's a T fitting that wants to trap air. Black-bleeding always works for me.

That being said, it can also send any dirt in the fluid back up the line, and so I always finish with a regular bleed, once the air is out, to remove any dirty fluid.

 

If there is any air in the system this will get it out. I've used this method where the bleeder is broken off and the system couldn't bleed conventionally. It sounds like its just air in the lines.

 

Any luck Rockable?