Rear Hatch Leak
 

I have searched and it seems most of the problems with the seal are at the top of the hatch with water dripping down onto the rear seats. My sons 88S4 has a rear hatch leak but the water is coming in at the bottom and dripping down onto the tool kit. My first guess is the seal but it appears to be in pretty good shape and does not seem to be flattened (though I don't have new one to compare it too). I did place a piece of paper on the seal and then close the hatch, I was able to pull the paper out without much effort at all. It did feel like it was touching, but barely. The two stops are turned all the way in so I don't see how the hatch can close any tighter. Im also having a hard time figuring how the water can migrate up and over the seal.

At $160 for a new one I just wanted to see if you guys had any other suggestions as to where the water is coming from.

Good question and I have the same issue. I just picked up this car and the rear passenger seat is almost ruined because someone let this issue continue. I am installing sunroof seals and clearing those drains but I suspect it could be the top of the hatch gasket. Look forward to the thoughts from the more experienced.

Check the bottom side of the hatch for water coming out around the stop. Water gets inside the hatch thru the clip screws that hold the rear glass in place. Mine leaks on passenger side and puddles in spare tire well. Local glass shop has seen this and says you have to remove window trim, seal around the screws, let it cure, replace trim. Trim comes off fairly easily. The clips that hold the rear glass has slots in them that secures the trim.

Good call and I will check out out

The spot where the hatch harness goes through is prone to leaking, and the top corner of the door is also a spot of ingress. Grab a hose and have someone run it over the car as you sit in the back seat and you should be able to find it.