Hello

Should I be concerned, or if they all do this?

My '87 syncro makes a whiny-buzzing sound after I shut the engine off.  It
appears to be from the small (about 1" diameter) plastic canister in the
vacuum line, under the floor below the middle seat.  It's just before the
bulbous thing that I assume is a vacuum reservoir for the diff lock.

My guess is that it's a one-way valve to keep a good vacuum in the
reservoir, and that leaking back is either perfectly normal, or at least no
big deal.  I don't think it's causing a vacuum leak, just maybe not holding
vacuum in the reservoir as well as it should.  My only symptom is this noise
(which probably happens when the engine is running as well, but I can't hear
it.)

Thanks for your wisdom.

Raymond