> What is the best way to check for water leaking into the car.
On a nice warm day I put the bilge plug in and filled my Amphi up with a
garden hose with a few inches of water (sloshing around some marine bilge
cleaner in the process) then came back later to look for wet spots on the
body and in the driveway. Another test is the old
pull-out-the-backseat-and-take-her-for-a-swim looksee. Heavily chalking up
the door-at-door seal, closing, latching, opening and seeing where the
chalk's missing on the door-at-door seal is another diagnostic method I've
heard of to rule out door seal leaks is taping up the doors. Then there's
the old take-a-swim-in-shallow-water-and-open-the-trunk process. Another
likely favorite leakspot might be the around the jack mounts, where it the
body can corrode nicely. One can easily peel away the interior siding just
below the door in the passenger compartment and observe the hull's integrity
in the drink.
> How can you tell which seals need to be replaced.
By the leak's location. When in doubt, renew.
> How much water is acceptable.
Some folks run quite happily with the bilge pump switched "ON" spewing out a
geyser the entire time in the drink. Me? I would find that a wee tad nerve
racking. More than 30 second's bilging every five minutes or so would send
me to shore, or maybe a bit more frequently in really choppy conditions.
Whatever your own predilections, I strongly urge you to install a backup
bilge pump as described at http://www.geocities.com/SoHo/8389/autosploodge.html. The original CAN clog
or fail. I've seen it happen, and then you're in real trouble.