We recently published an article on how to seal your hatch and stop the annoying leaks. While this was pretty comprehensive, a few emailed questions have prompted me to provide a little more information – specifically, how to ensure it is all aligned properly so that it seals around the body.
A few weeks ago we had a 944S come into the shop with a leaky hatch – not at the top, but the owner complained about exhaust smell into the cockpit. We checked the exhaust system and found that the only place that the exhaust was getting out was at the rear where it is supposed to come out. That made us immediately suspect a leaky hatch.
We found that the hatch itself was mis-aligned – it was sitting “crooked” in the body. The shot line between the roof and the top of the glass was very close on the drivers side and not-so-close on the passenger side. While the difference doesn’t seem like much, it is enough to cause the seal to be loose on one side at the bottom sides and tight on the other. It took a few minutes to remove the sunroof gear cover, loosen the Allen head bolts holding the hinges in place, and get everything back in line and square.
Next we inspected the seal itself, and it was nearly new. The seal, which came from Kyle Youst at Only944.com, is a one-piece circle, so there is no gap at the bottom middle that can increase in size over time. No leaking in a big gap there, and the seal was in like-new condition.
We used the method described in our article Fixing the Hatch to align the latch pins. With that done, the hatch closed nicely, seemed tight and secure, and no rattles, and looked like a nicely finished job. Not so fast.
The last step is to take a sheet of paper folded in two, open the hatch, and put the paper between the hatch seal and the hatch itself, then close the hatch. If the paper slips out easily, the hatch and seal are not sealing properly. Repeat this process on both sides, all the way around and to the bottom of the hatch. (Note – you can print this article, then use it to check the hatch seal!)
If you find that the paper pulls out easily at the bottom, it means that your pins are not pulling the hatch down far enough to form a good seal. Shorten the pins a turn or two at a time until you get a good seal and the paper will not pull out. Remember that too tight makes it hard to close, and too loose makes it leak.
I hope this helps you get that pesky rear hatch working better than new!