Brake Pedal Not Returning

[Lurker27]

Driving normally, after braking i noticed that the brake stuck in the "lightly braking" position. While coasting at around 25MPH the car would slow down and come to a stop within about 800-1000 feet. I could use my left foot under the brake pedal to pry it up while driving (automatic trans) to alleviate the braking, but even doing this, I could not fully return the brake pedal. Brakes function normally, but seemed very sensitive, probably since the brake was already partially engaged. Nothing is caught on or rubbing on the brake pedal itself. When i stopped the car, I felt each wheel and I didn't notice a huge difference it temperature difference between the four wheels. The front wheels seemed slightly hotter than the back.

Preliminary research suggests:

Air in system (Bleed system)
Clog in system (flush system)
Maybe a bad ABS servo?

Any experience in this matter is helpful.

tl;dr: Brake pedal is stuck slightly depressed.

[whiltebeitel]

Perhaps your pistons are not fully retreacting.

[Lurker27]

The seals in the master cylinder could be swollen I guess, although would that affect the pedal?

[Beej '86 325es]

Does the car pull to one side at all when you're not braking? If a piston is sticking, the car would pull to that side...

[jlevie]

This sounds like a problem with the master cylinder, brake booster, or pedal box.

[Farbin Kaiber]

sounds like blown booster, or seals in master gone.

[Lurker27]

I don't think it's the booster; The pedal doesn't feel hard.

[jlevie]

It still could be the booster. A bad valve could have boost on even though you've released the pedal. As a check, pull the vacuum line from the booster and plug it. Then see if the pedal still sticks low.

[Lurker27]

Will do jlevie, thanks!

[Lurker27]

Solved; it was the pedal mechanism!