Brake Bleeding w/ ABS, PowerBleeder - Air?
 

I've replaced rotors and pads all around, replaced 1 caliper and rebuilt the other 3 (which are still quite rusty on the exterior).

I cannot get the Passenger Rear to bleed properly. I get fluid at the other 3 lines, but at PR I get a mixture of air and fluid. At first I wondered if it was the old rusty bleed nipple, so I got speed bleeders all around, same issue.

I've tried bleeding with the powerbleeder as well as the 2 man.

Here are my hypotheses:

1) The bore the bleed nipple screws into is too wide. At 1/4 to 1/2 turn, the bleed screw has a little side to side play in it. Could this alone cause the air? If so, new caliper?

2) I blew the seals in the Master Cylinder somehow.


As an aside, I built the garden sprayer-style powerbleeder, using an old Benz cap. I can't get it to not leak fluid - I put a bunch of plumber's tape on the reservoir threads to minimize it, then stuff paper towels around. Others have a similar issue?

Thoughts ?

Thanks,
Bruce
70k 190D 1989

you need a seal on the cap... the factory cap is vented, and there is a passage that allows fluid/air to escape.
I got the GM cap, it's the same size, and has a full size rubber seal, then filled in the air bleed passage.

That would explain the leaks at the reservoir. What GM model cap did you get?

PS - One other piece of evidence. I had brake fluid leaking past the bleed screw down the caliper, despite a hose tightly affixed on the end of the bleed nipple.

I'll be back working on the car tonight, appreciate any thoughts folks had. I've read mixed reviews about using teflon tape on the bleed nipple threads, but seems like that would be a logical next step given the play and the leaking fluid around them.

I would simply replace the caliper instead of messing with whatever problematic piece that I don't have access to. That will give you a finished system with a lifetime warranty and you can move on.

ATE and Bendix both made calipers. Either will work as long as the same brand is on both sides of an axle. Both take the same pad. A1-cardone is the most prevalent rebuilder at the McParts stores. Buy locally as Cardone has QC problems. I haven't had a problem once installed but have had wrong part in correct box. ie rear packed in front box, left packed in right side box.

Change the hoses and wear sensors at the same time. A little Sly-glide on the pins helps keep the pads from sticking. Buy MC from Peach as they have/at least had good new units for not much. Measure the rotors. New they are thick enough to cut once.

There are also good low dust pads on the market.

Also, make sure your rubber brake line hoses are not degraded and/or cracked.

Continuing to see challenges on the bleed job. Have a firm pedal when car is off, but very soft when I turn the car on.

I replaced the MC, bench bled it first, because I suspected that I had ruined its seals in the process.

I'm powerbleeding at 10, then 20 psi.

I get fluid with no bubbles coming out of all four corners. Interestingly though, the fluid isn't a continuous drain. It comes out to a given length in the clear hose attached to the bleed nipple, then stops.

Is that normal?