Leaking glass hatches that have separated from the frame at the top of the hatch are a continual problem with our cars. Often misunderstood, we will talk about why this happens, how to fix a leaky hatch, and how to keep it from happening again.
The glass hatches will eventually leak, and when they do, they leak at the top next to the roof, normally near one or both hinges. In some cases, water will drip down onto the top of the back seat, discoloring it and eventually damaging the upholstery. (If yours is leaking, fold the seat down so that you don’t ruin the seat.). In extreme cases, water can collect on the rear seat floor.
To understand why this happens, you have to understand how the hatch is designed and built. There is a metal frame surrounding the hatch that is bonded (glued) to the glass. The frame has two hinges that bolt to the body at the roof, and is latched by two latch mechanisms at the bottom. The pins fit into the latches in the body, and alignment of these pins and latches is critical to the operation of the hatch. The whole thing is sealed by a rubber seal on the body. Finally, there are two “shocks” that facilitate the opening of the hatch.
When the hatch fails, most of the time it is a separation between the glass and the frame at the hinge area. But the first indication of impending failure is NOT a leak, but instead shows its ugly head in the form of difficulty opening and even closing the hatch. It is a rare 944 these days where the hatch will open with the electric release button under the dash on the kick panel, but more on that later.
If you have to hold the key to the left and jiggle the hatch (or man-handle it) to get it open, the hatch is on its way to failure. The pins-and-latch mechanism is dependent on proper alignment, so when the glass and frame start to separate, the whole thing goes out of alignment at the latch, making it difficult to open. There is a problem, not at the latches but at the top of the glass. And if this is happening, I will bet that there is also a bit of creaking at the hinges when you open the hatch.
As the hinges age, they pick up a little corrosion and get stiff. Opening and closing the hatch with sticky hinges sets up a situation where the frame twists slightly every time you open and close it. That twisting force on the frame tries to pull the thin metal frame away from the glass, and eventually does just that – separates the glass from the frame, causing a leak.
We also have failures in the shocks that hold the glass up. OEM shocks are expensive, so we opt for the parts-store or online sources for new ones. Unfortunately, these lower-priced shocks may be too powerful for the hatch. If you look at your hatch in the closed position, you will see that the shocks are fully compressed, pressing against the hatch and pushing it back against the pins-and-latches and away from the hinges. Again, this can aggravate the situation by pushing the frame and glass away from each other at the hinge.
So between sticky hinges and aftermarket shocks, the glass-to-frame bond will eventually fail.
There are many, many online fixes available, and we here at 924S944.com have tried a few of them. Our conclusions are that this is a job that is best left to the professionals, as long as that professional that you find knows what to do.
Silicone stuffed between the hinge and the glass will not work. The problem is that the glass and the frame are coming apart, so filling the void with silicone may fix a leak for the moment, but it does not represent a real repair.
To effect a repair that will last for a while means that you have to remove the hatch and take it to a glass shop – preferably an automotive shop that has experience with bonded glass-to-metal joints in cars. You may have to interview several shops to find the right one. Don’t let people learn and practice on your hatch!
The technician will separate the frame the from the glass all the way across the top of the hatch, carefully pulling it away so that he or she can clean any old bonding material from the glass and frame. With everything clean, the tech will use a primer substance to prepare both surfaces, then use an epoxy bonding agent specific to glass and metal to reattach the frame to the glass. Ratchet straps are then applied to push the frame and glass together securely while the epoxy cures overnight.
Once you get your repaired glass back from the shop, check the hinges to be sure that they work properly and freely. A little graphite lubricant can go a long way – graphite will not attract dirt and helps to keep the functioning smooth for a long time. Once the hinges are working properly, reinstall the hatch. There is some adjustment in the hinge alignment at the top, so pay attention to the “shot line” or gap between the hatch frame and the body so that proper alignment is created.
Alignment of the pins and latches is an easy job with a trick or two. Use a 10mm wrench to loosen the latches in the body, then snug the nuts back up until the latch can move around a little bit but when moved, will stay. That’s more than finger tight, but less than tight. With that done, carefully close the hatch, allowing the pins to lightly contact the latches without actually pushing them into latch. What you are doing is allowing the pins to push the latches into alignment, self-centering the latches with cones of the pins. Before closing the hatch completely and allowing the pins to latch, open the hatch and tighten the latches firmly. Then the big test – close the hatch. You will find that the hatch will open and close easily and freely. It may even work when you push the button under the dash.
Of course, if the hatch needs to be jiggled to open it or it won’t open at all, the alignment is not perfect. Repeat the process until you get it right. (If the hatch will not open at all, you can climb into the hatch area from inside and slightly loosen the latches with your 10mm wrench – difficult but about the only way to do it.
The design and construction of the heavy glass hatch is not perfect, but with careful repair and proper attention, they can be made to function properly without leaks for many years.
And here is a disclaimer – folks have said that even with a good repair, the hatches will separate again. This can be true, but remember that the original design was not the best, and failure of the bond between glass and frame is inevitable. Keep the hinges lubricated and the latches aligned, and you should have years of trouble-free hatching.
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Kevin Duffy is an Associate Professor of Criminal Justice at Daytona State College in Florida and a dedicated car guy. He divides his time between teaching criminal justice topics in the online environment and working on/driving cars, particularly Porsches. Kevin is one of the principals in InspiringLifeOver50.com.