A list member asked if perhaps I'd just turned on my rear heater for the
first time this season.

*I didn't, but I remember now that when I drove the van off after the
pressure test, I heard the rear heater on full blast, pulled over, & shut it
off.  I never have need of the aux hearter.

I don't know why the mechanic turned it on, but he did.
Now, I am waiting to hear why this clue re the rear heater might explain the
loud gurgling/swishing sound I'm hearing front & rear...

Phaedra