1982 usa 320i manual
I just removed the brake master cylinder to replace it as I have no braking power and bleeding the brakes yields endless air bubbles. I discovered when I depress the brake pedal I can feel air seeping out the break line ports on the master cylinder.
So i removed it to check it out/ replace it. Now when I look inside the brake booster to make sure it is all dry inside, I see a large rubber o ring hanging inside on the push rod. This is not the seal that goes between the master cylinder and the booster as that is still on the master cylinder and in decent shape. I can't seem to find any diagrams on the internals of the booster so I am wondering where this o ring needs to go. I have supplied an image looking inside my booster and a link to the image if that doesn't work. Thanks for any help!
https://imgur.com/YhsA3rm
