My 88 rear hatchback leaks during heavy rain. It's possibly coming in between the bottom glass and rear panel but not sure. I have a small rust spot forming at the bottom but don't see a hole. I checked my weather strip and it feels soft and pliable. The contact area looks to be ok. I can't pinpoint the leak but the bottom of my trunk gets moist after a good rain.

 

This post reminds me. My hatch leaks from the bolt holes where it attaches to the body. I gotta go fix that!

 

mine is the same if you find out why post it here so I will know too

 

The bolts that go through the body have a sealant on them that shrinks over time. Go to the hardware store and get a roll of the window sealant aka dumdum