A bit of history - I replaced one lower ball joint last week. It was pressed in by the shop. Also the struts arrived yesterday so I went ahead to put everything back together on passenger side. I did not touch the driver side. The caliper was removed when I removed the strut and left hanging, with support, for 2 weeks. I installed and caliper and pushed the brake piston in to reinstall the pads. All is good.

I tried to press the brake to sit the pads. The brake pedal traveled all the way to the bottom but this is expected as I pushed the piston in. I pumped the pedal a few times and to my horror it still travels all the way to the bottom as if there is air in the system. I have been driving it before I decided to change the ball joints and the car is on blocks for 2 weeks. The brake was good before this BJ endeavor. What could have happened? I can bleed the brake but I am just puzzled.

Any info is appreciated.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Your master cylinder pistons use less than half of the master cylinder under normal use. 20-30 years of moisture in brake fluid causes corrosion where the piston doesn't continuously scrape it off. Then one day you send the pedal to the floor and damage the piston seals on the corroded sections. It can happen, right?

Sixto
87 300D