W123, new master ATE, all new hoses

Seems like it requires voodoo

so many folks say they do it "this way" or "that way" and "it never fails"

some swear by pressure, some by pump and hold

deviations from the "normal" are the rule. Its kookoo.

RE: bench bleed: I get zero bubbles after just a few strokes

and a sinking pedal, ie still air in MC

I tried removing MC from vice during bench bleed , rolling it around side to side, front back That way I started to get more bubbles after the usual routine, getting zero bubbles beyone the first few strokes,


In case anyone is following this saga, I had the rear calipers on the car installed L caliper on R side, and vice versa, so it did not bleed air, so now deeply soft pedal is resolved, but is sinks ever so slowly and requires big time pedal pressure , abnormally big pedal pressure

Sounds like a booster problem to me.

Regarding bench bleed: I had great success with this method "in situ". Install the master cylinder in the car completely (all lines attached, reservoir in place). Fill reservoir with fresh brake fluid. Attach a hose (cheapo fish-tank air line hose from Wally world did the trick for me) from the front left wheel caliper brake bleed valve, and open the bleeder valve. Route the hose from the bleeder valve so it empties into the reservoir. Pump the pedal until the fluid from the hose has no bubbles. Bleed the rest of the calipers per normal procedure.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

First time I ever heard of runnining a line from front drivers side bleeder valve back to M.C. hey might work never tried it. Rocket I had a strange pedal too with the symptoms you describe, I first tried a good bleed on the system hoping that would correct it but it did not changed the symptoms a little but did not correct it. I bit the bullet got a rebuilt M.C. carefully bench bled it seemed I was better if I went a little shorter then full stroke with the plunger if I went full stroke I would reintroduce new air in system. Got all air out put it on and pressure bled with home made bleeder with about 20 psi. on system one wheel at a time checking fluid level in master between wheels and end result was great brakes. I think someone said that if you want to check to see if you brake booster is working is to push pedal down w/o engine running then start engine pedal should rise if booster is working not sure if this is correct or not but is what I have read.

I now seem to have brakes at or near 100% based on 5 yrs with this care

It still seem to be in the realm of voodoo

all I did was bench bleed and caliper bleed, over and over

Bench bleed: I got a few bubbles in the first few strokes then nothing

At the end during bench bleed I removed the MC from the vice and tiped it back and forth, tapped it , to move bubbles around

THEN: I got a few more bubbles.

Then it got better.

I also propped the pedal down a bit overnight, it also seemed to occasioned improvement overnight. Stretch be boss.