Is it normal for the sunroof to drip water into the drainage channel?
3 Answers
It is normal for the sunroof to seep water into the drainage channel. The left and right sides of the sunroof are two sliding rails that ensure the sunroof slides back and forth. At the front corners of these rails are the sunroof's drainage holes. If the drainage pipe is clogged or broken, water will seep out from the sunroof gap and drip into the interior. A broken pipe can also cause water leakage in the car's A-pillar or C-pillar. Another issue is the aging of the sunroof's sealing strip, which can lead to water seepage. Below is an introduction to sunroof leakage issues: 1. Deformation of the sunroof sliding rails: Rail deformation is usually caused by movement obstruction, where the motor forces the rails to move back and forth, stretching and deforming them. This results in the sunroof glass not closing properly, allowing rainwater to enter the car. If there are no separate rail components available, the entire sunroof frame assembly must be replaced. 2. Breakage of the sunroof lift arm: When the sunroof slides to the front and closes, if the lift arm is broken, the sunroof cannot rise to be flush with the roof, creating a depression. Rainwater will then leak into the car along the sunroof edge. This also requires replacing the entire frame assembly to resolve. 3. Aging of the sunroof waterproof sealing strip: Especially in cars over 10 years old, the aged sealing strip cannot form a tight seal with the roof, allowing rainwater to seep into the car.
My car's sunroof does the same thing, and it's actually completely normal as long as the water properly drains into the drainage channels. The sunroof gaps are specifically designed with these drainage channels, and rainwater dripping through the gaps around the glass is the correct water drainage path. You can test it by pouring a bottle of mineral water along the edge of the sunroof—if the water flows down the pillars and disappears, it means the drainage tubes are clear. But if the water pools in the sunroof and doesn’t drain, or worse, starts dripping onto your head, then there’s definitely a problem. Personally, I use a thin wire to clear the drainage tube outlets in the A-pillars every quarter. Parking under trees often leads to leaves and mud clogging the tubes, which can cause water to overflow into the car. This check is super simple and much easier than dealing with moldy interiors later.
That day while washing the car, I noticed water dripping from the corner of the sunroof and nervously asked the mechanic about it. The mechanic pointed with a screwdriver: 'See this black recessed channel? It's the drainage gutter—rainwater is supposed to collect here. As long as the drain holes aren't clogged, the water will flow through tubes inside the A-pillar or C-pillar and exit underneath the car.' He taught me to use a syringe filled with water to squirt into the drainage channel—if the water instantly gushes out from the drain outlet behind the tires, it's functioning normally. The key point is that aged sunroof sealing strips can also cause leaks, especially in cars over six or seven years old. If the strips crack, heavy rain can bypass the drainage channel entirely and soak the headliner directly—this requires replacing the strips. Don't neglect maintenance; cleaning small debris from the channel every six months makes a big difference.'
