Update:

I connected the direct brake line (not brake hose to the brake caliper) on the front left wheel area using the vacuum pump. Pressure on the vacuum gauge was steady not going low at all. Small pockets of air and brake fluid shown in the clear plastic tube/hose, brake fluid with no consistency of flow, just sporadic.

I assumed at this time, the brake line is ok.

I then tested the same process above using the Motive Pressure bleeder. No movement on the clear plastic tube/hose. Something is blocking the brake fluid from going into the brake line. Brake pressure bleeder is still ok.

I suspected internal bleeding issues on the Brake Master Cylinder (seals worn, tear, etc.)

I reinstalled the brake hose on the brake line and connected to the brake caliper along with the breeder screw/valve.



When I first started to bleeding the brakes using the vacuum pump, the flow of air bubbles were sporadic along with solid brake fluid in intervals, and not long solid brake fluid flow afterwards, (minus air bubbles) that should be consistent. Am I correct? The same thing happened using the Motive Pressure bleeder. Could be the cause of internal bleeding issues (inside seals worn out, tear, defective) of the brake master cylinder? Locations of air leaks?

I removed the Master Brake cylinder and replaced with a new one. Just had to be extra careful while removing the brake master cylinder. As previously mentioned in the first post that started the series of events, (push rod felled out of the brake booster) I tried not to disturb the push rod inside the brake booster so it will not fall off.

I also noticed the brake hose on the left front (driver's side) appears to be flaky/cracking opening when bending the rubber near the end of the brake hose by the brake caliper. That could be the source of air leaks or not. I, then, decided to ordered four new brake hoses (two in the front, two in the rear). That way, new brake master cylinder, new 4 brake hoses should eliminate pockets of air and pockets of brake fluid coming out of the brake screws/valves.

The front two brake hoses were somewhat difficult to removed. So I applied PB blaster and let it soaked for about 30 minutes. I do not want to stripped the brake line nut (11mm). Fortunately, both old front brake hoses were removed from the brake caliper and the brake line.

I was trying to removed the 2 rear brake hoses when I noticed a very stiff resistance, even though I used the flare nut wrench. Again, I applied PB blaster to both nuts each on the brake hose (11mm brake line, 14mm brake hose). Let it stand for about 30 minutes. No luck in removing the rear brake hoses. I decided to cut the old brake hoses as closed as possibly to the bottom of the 14mm nut using box cutter knife. Not even close enough to cut. So I used long garden sheers and it cut really quickly.

I used deep well 14mm 12 point socket to remove the bottom brake hose with enough room inside the deep well 14mm socket. I slowly turned the ratchet left (lefty loosy, righty tighty), so it won't damaged the 11mm nut (with the 11mm flare nut wrench inside to counterbalance the other 14mm brake hose on the top) on the other side of the brake line separated by a brake line retainer clip. Used the wd 40 lubricant on the outside threads of the brake line 11mm nuts to make it easier to tighten smoothly with the brake hose. I used the technical article in regarding to removal/installing the brake hose: https://www.pelicanparts.com/techarticles/Mercedes-W124/70-BRAKES-Brake_Line_Replacement/70-BRAKES-Brake_Line_Replacement.htm



After installing new master cylinder, 4 new brake hoses, and put in DOT 4 brake fluid in the brake fluid reservoir, I pushed in the brake pedal. No pressure at all. The brake pedal went down easy peasy. No traction at all. I went over to the see the brake master cylinder area and saw brake fluid all over the bottom of the Brake Master Cylinder.


I could not figured how that happened. Checked all brake lines and hoses and making sure they are all tight. I looked at the Brake Master Cylinder and make a comparison with the older Brake Master Cyclinder. There I saw the difference. On the older Brake Master Cylinder, there was a block brake line port in front, meaning I used two brake lines to connect to the Brake Master Cylinder 2 ports. On the new replacement Brake Master Cylinder, there were 3 open brake line ports. So I went to an auto parts store to get what is called Invert brake line plug or MASTER CYLINDER PLUG. In addition, I got teflon tape (Thread Seal Tape) to cover the threads on the plug to make sure there will be no brake fluid leak from the brake line port on the brake master cylinder. I put in the brake line plug along with teflon tape on the threads inside the 3rd open brake port on the Brake Master Cylinder . See the picture with a red circle of the third port with a plug inside.

Put in back the brake fluid reservoir on the top of the Brake Master Cylinder. I poured the DOT 4 brake fluid in the brake fluid reservoir. Checked all connections including brake lines are tight and not leaking brake fluid.

I started the engine to get the pressure build up and pressed the brake pedal. Now I am getting traction on the brake pedal. I noticed on the instrument cluster panel showing ABS, ASR, wiper fluid and parking brake lights on and will not go away. Removed the positive battery cable to cleared the code 4 on the 16 pin Self test Diagnostic module (DM) and put back the postive battery cable on the battery.

I started the engine and pressed the brake pedal. Good traction, no spongy-like feel. Brake pedal stopped at approximately 5 or 6 inches above the floor. I did the abs sp bleeding and a few spots of brake fluid came out. Tightened the sp brake bleeding screw. Turned off the engine and restart. The ABS and ASR instrument cluster panel lights were OFF. The only thing left on the instrument cluster panel lights were still on is BRAKE (parking brake light?) and the window wiper fluid lights. If it is the parking brake light on, does that mean because I already dismantled the parking brake assembly prior to removing the brake booster earlier? I believed the brake light came on because of the parking brake cable was dismantled earlier.

I then started the bleeding brakes process using the Motive Pressure Bleeder. Started right rear, left rear, right front and finally the left front. I noticed brake fluid leak on top of the brake fluid reservoir on the black cap. The black cap had a line crack opening, shooting brake fluid out. I replaced the black cap and no leaks. Very little brake fluid came out using the Motive Pressure Bleeder, just a few air bubbles. What am I doing wrong? Did I overlook something? The Motive Pressure Bleeder still maintained pressure throughout the brake bleeding process.Brake Fluid is still full inside the Brake Fluid reservoir. Brake pedal is still in good traction as described earlier. Any comments, feedback, advice is greatly appreciated.

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I did a little test drive on my property. Spongy feel brake pedal. No direct stop after pressing the brake pedal, just sliding a few more feet before stopping. ABS ASR and Brake light on the instrument panel cluster. I felt like it start all over again. What am I missing here? Will continue to work on the braking issues and I will keep up to date on my progress, if any.

What pressure is the Motive Bleeder reading? Will it hold pressure?

ABS and ASR light can be a bad voltage regulator. What voltage is the system charging? This shouldn't affect stopping power though.

Are all bleeder screws on the top of the caliper? Does the ABS have a bleeder screw under the black plastic cover?

Hmmm.... puzzling to say the least.

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Sugar Bear, to answer your above questions:

What pressure is the Motive Bleeder reading? The pressure guage is stable no up and down movement at around 15 psi as recommended.

Will it hold pressure? yes

ABS and ASR light can be a bad voltage regulator. What voltage is the system charging? This shouldn't affect stopping power though.

The answer is I tested the battery charging system using a battery tester. Results shown the engine running and the voltage shown 14.4 volts good, stable and solid and no decreasing voltage .

Are all bleeder screws on the top of the caliper? YES.

Does the ABS have a bleeder screw under the black plastic cover? YES.

I checked out the two ABS relays on top of the ABS hydraulic pump with ASR. I removed both ABS relays and inspected them both. No sign of dirt, rust, clear contacts. However, the 4 pin ABS relay when I shake it, I felt something was loose, nothing solid. The other ABS relay 6 pin, nothing felt moving inside.

Also, I started the engine and few minutes later, the ABS and ASR lights on the instrument cluster panel came on. I pressed the brake pedal. At first, solid traction about 6 inches above the floor. Then slowly, (already pressed brake pedal) went down to the floor. In addition, the rear brake lights were on and stayed on, even though I did not pressed the brake pedal.

Any comments from anyone? Stay tune for further updates.