In a message dated 3/15/00 7:38:36 AM, kdlewis@JUNO.COM writes:

<< Forget the pressure test, it's pretty useless. The pressure cap
limits pressure to about 10 to 12 psi.
To verify have a mechanic "sniff" the overflow tank with the
wand on his emissions tester. If any hydrocarbons are present run don't
walk from this one >>

Steve:
The pressure test is most conveniently performed using the PRESSURE CAP
OPENING as the test port.  You will be surprised at how small of a leak will
readily show.  Just have patience and allow the system to sit at test
pressure for a while.

I do not know how well one can sniff an overflow tank; I do know that there
are inexpensive chemical test kits available designed specifically for this
application.
Rich