Honda Accord - trunk leaks

I got a 1990 Honda Accord DX. Starting this summer, when it rains,
the trunk gets wet.

Anyway to find out where it leaks? I suspect it's the rear window
but where exactly? How to find out where on the window leaks?

 

Tail light gaskets.

 

.... which is a very common leakage point on c. 1990 Hondas. Many reports are in
the archives on this.

If it appears to be the gaskets, one may disassemble the taillight assemblies
and either

1. Buy new gaskets. Maybe $6 apiece. Replace.

2. Buy temperature appropriate silicone caulk. Remove old gaskets. Clean
thoroughly. Caulk both sides of the gasket where it contacts car parts.
Re-install. The drawback to this is that, next time the gaskets leak, cleaning
off the old caulk is a pain in the neck.

I used 2. above almost two years ago on my 91 Civic's taillight gaskets. No
problems since.

 

take out the taillights. see that disintegrated piece of foam rubber?
apply a 1/4" bead of GE 20-year clear or black silicone where that foam
rubber is. reinstall, and all will be well until at least 2024.

 

use a generous bead of the GE 20 year silicone, and it wont leak.

i caulked a tub using that stuff about 15 years ago, and it held up
well. the floor didnt, requiring replacement this past week. so the tub
sunk, and pulled away from the wall and caulk. so i had to shore
everything up, replace the floor, and recaulk. getting the 15 year old
caulk off was a PITA... it was still as pliable as new, though.

 

Tailights leak a lot but the body vent in the left fender can also leak.
Lower the lest side of the rear bumper to access and reseal.