ALDA valve (on top of IP) question
 

As I had to take out the ALDA (W124 '87 300DT) because of fixing the stop valve, I noticed that it does not hold neither vacuum nor pressure. I took it apart (four philips on the bottom) to see no rubber membranes inside (although I saw hint that once there may have been one). Am I correct assuming that both the top metal membrane and the bottom metal membrane should have a rubber membrane around them?

Thanks,

Greg

No. They are bare metal.

Don't worry about it not holding vacuum, it will never see vacuum in operation. The ALDA won't hold pressure when it is removed.