The 300ZX water leak repair became top priority soon after I bought my Z. The previous owner had kept the vehicle in the garage for most of its life. When I purchased it and left it outside for the first time the rainwater quickly found its way inside the rear compartment and formed a generous sized puddle. It turned out that this water leak is quite common on both the 280Z and 300ZX.
Unfortunately I wasted some money on trying to get this leak fixed before I looked into technical service bulletins. I figured since the hatch compartment was wet that the aging rubber seal must be the cause of the water leak infiltration.
I purchased a new hatch gasket from the dealership and this cost me around $150. After replacing the seal I anxiously waited for the next rainfall to come and go. To my disappointment after a hard rain the rear hatch compartment was again like a miniature swimming pool.
How to Repair the 300ZX Water Leak
After my first attempt turned into a costly failure I looked into some factory issued technical service bulletins as well as performing an Internet search. Many Z owners had reported the same type of rain water leak. Find out more about Car Repair Bulletins here.
The Nissan service bulletin stated the water was entering from the tail light assembly. The taillights on the 300ZX attach through the rear compartment wall. Apparently water was dripping onto the long threaded posts and traveling into the rear hatch compartment.
The fix was to completely seal the taillights assemblies thereby stopping the rain water from reaching the threaded screws. it’s the old diverting the water in the other direction trick. The silicone sealing job didn’t look very neat, because I rushed it, but was very effective at stopping the water.
I rarely opened the rear door because the pistons that hold it up where blown out so, when the hatch lid was closed there were no signs of silicone. The messy silicone seal job was my dirty little secret and couldn’t be seen by others checking out the overall beauty of my 300ZX.
Why you have to fix water leaks
Water collecting in the rear hatch compartment can be very destructive to the health of the overall automobile. Yes, the main problem will be rust developing in the bottom of the hatch compartment. Trust me when I say repairing the rusted rear compartment is a lot more difficult than fixing the water leak.
Another destructive part about having a pool of water sloshing around is the increased humidity level inside the vehicle. Musty smells and mold are the mild side effects. The evil part is, it can greatly accelerate corrosion throughout the interior spaces of the automobile. Things like connectors and wiring harnesses will start to turn green and provide intermittent connections quickly. Also components such as control modules and relays can be negatively affected by a hatch full of water.
One of the most destructive properties of an interior compartment full of water is the effect on the grounding locations. Automobile system ground connections corrode quickly in a humid environment.
Poor ground connections are often the first problem that develops from an interior water lake. Many weird electrical issues can start to develop from poor or intermittent ground connections. If you’re interested in what other repairs this car needed you can visit the Z section of this blog. This next link takes you there from this page about 300zx water leaks.