Why is there water inside the car when the sunroof doesn't leak?
4 Answers
If the sunroof doesn't leak but there is water inside the car, the following areas should be checked: Loose door seals: Check if the sealing strips on all doors are damaged. Solution: Replace the sealing strips. Clogged drainage pipes: Check if the drainage pipes under the chassis are clogged, causing water to enter the car from below when driving through water. Solution: Unclog the drainage pipes. Leaking heater core: If the heater core inside the car is cracked, it can cause antifreeze to leak into the car. Check if the antifreeze level is low. Solution: Drive the car to a repair shop or 4S store to replace the heater core.
A while ago, my friend's car was always damp. The sunroof was tightly closed with no signs of leakage, but after checking for a long time, it turned out to be an issue with the air conditioning system. When the car's air conditioning is on, the evaporator produces condensate water, which is supposed to drain out through the drainage outlet under the chassis. If that drainage outlet gets clogged, the dirty water can be blown all over the car by the AC blower, especially under the passenger seat—it can become like a fish pond. Alternatively, if someone spills a drink in the car or leaves a wet umbrella inside unnoticed, these unnoticed water accumulations can gradually soak the carpet. Another common issue is aging door seals, which can let rainwater seep in through the gaps during rainy days, often going unnoticed.
I often help people inspect used cars, and it's really common to find water leaks inside the car that aren't from the sunroof. Most of the time, it's because the drainage holes in the exterior water channels are clogged! For example, the water channels around the windshield and behind the engine compartment can accumulate a lot of leaves and branches over time. When heavy rain comes, the water can't drain properly and seeps into the cabin through gaps in the firewall. Another hidden culprit is the aging or cracking of the sealant around the window edges. During high-pressure car washes or heavy rainstorms, water can quietly seep in through these small gaps. Water leaks in the trunk can also affect the interior, such as when the tail light seals age or weren't properly reinstalled after removal. It's often hard to trace the source of water entering these areas. It's best to find a professional who can use a water spray to simulate rain and locate the source—just relying on visual inspection makes it too difficult to find.
This issue is really frustrating! Last month, I was completely fed up with the pool of water on the front passenger floor of my car. After troubleshooting, I found out that the sunroof's drainage pipe was clogged. Those tiny holes around the sunroof frame may seem insignificant, but they were completely blocked by dust and mud, causing water to back up and flow down the A-pillar under the floor mat. Without disassembling, it's impossible to tell where the water is coming from. Some cars with poor sealing, where the windshield adhesive isn't tight enough, can leak water directly down the dashboard. Also, if the floor mats are installed in a way that blocks the drainage outlet at the bottom of the door, rainwater can accumulate inside the door and suddenly flood the cabin. It's recommended to regularly clean leaves and debris from the sunroof drainage channels, and when washing the car, it's best to ask someone to use an air gun to blow out the drainage holes.
