piperspost@webtv.net wrote in news:28107-456CF13C-2792@storefull-
3331.bay.webtv.net:

Replace the taillight gaskets. Easy and cheap.

Problem is threefold:
1) water runs down the rain gutter on either side of the trunk/hatch,
right on top of the taillights, and
2) the nuts holding the taillights sometimes come loose, and
3) the gaskets themselves deteriorate over time

The gaskets are about 3/8" thick, and are soft foam rubber. they compress
to near nothing once installed.

Some will suggest siliconing the taillights on. I strongly un-recommend
this approach unless there is significant rust under the gasket.

Don't overtighten the nuts when installing the new gaskets! The last thing
you want to do is break the stud out of the plastic lamp housing.

One solution: Disassemble all taillight assemblies. Remove
old gaskets. Clean thoroughly with water. Let dry. Apply
weather appropriate caulking from your local hardware store
to both sides of the gaskets. Re-assemble. I did this about
four years ago with my 91 Civic. No leaks since.

You can buy new gaskets and get the same effect as well. The
advantage is that, if the gaskets leak again, you don't have
that nasty caulking to scrape off the car metal.

Is it an Accord?
Look in taillights after or during a rain, they may be filling up with
water.  If the gasket gets old the groove under the trunk pours water into
the light, when it gets half full it spills into the trunk.

I took out the light and sealed it with a bead of silicone.  I caulked
that body seam to encourage water to go away from the light.  Then for
insurance I drilled a 1/32nd hole or two in the bottom of the lens where
the water pooled.  Worked for me.