280Z To 280Zx A/c Upgrade(Vacuum Tank Swap)

[Dave WM]

Well I sliced it open and am a loss on how it is supposed to work. there is a small rubber thin disk. the small side has a tiny recess while the large side is a simple flat. the disk does not seem to be retained any way so its not like a flap. I have no clue how it is supposed to work. Perhaps when suction is applied to the small washer side, the idea is the recess is to keep the rubber flap from coming into contact with the hole on that side thereby maintaining  a passage for air. then suction is applied to the large side (motor off, tank under vacuum) the disk is allowed to move freely until it come into contact with the flat side hole and seal it up. Other than some slight deformity I can not see any real issue with the only moving part so I am at a loss as to why it was not working. No matter the cheap o from autozone works. I just like to solve mysteries.

[Dave WM]

for the fun of it flipped the disk over and glued it back together. the only deformity was the a tiny bit of a dimple. Perhaps over the years of vacuum the disk had been sucked against the port regardless of the recess, and had developed the dimple, which would overcome the recess and stick against the vacuum, conversely when the suction was applied from the bottle side, the dimple would not seal down flat. This is speculation of course, but flipping the disk should put the dimple away from the vacuum source and aid in the seal at the bottle side.

[Dave WM]

a little more info, per the FSM there is supposed to be "porous plastic" on the side of the rubber disk that goes to the intake manifold. This porous plastic it what holds the disk off the hole so the air can flow in that direction (from vacuum tank to intake manifold). I don't know why but there was NO porous plastic in my valve. Perhaps it disintegrated at some point. Anyway mystery solved as to how the valve works.

Edited October 8, 2016 by Dave WM