
This situation depends on whether it's the front drain pipe or the rear drain pipe that's clogged. If it's the front drain pipe that's clogged, open the sunroof and use high-pressure air to blow at the two front corners of the sunroof. This will clear the sunroof drain pipe. If it's the rear two drain pipes that are clogged, then you'll need to remove the interior headliner before you can use high-pressure air to blow them clear.

Last time my car got flooded, I found out it was because the sunroof drain was clogged. Here's a DIY trick: First locate the drain hole under the A-pillar, use a syringe to draw half a tube of warm water mixed with dish soap, and slowly inject it to soften the sludge. Then connect a rubber tube to a bicycle pump and gently pump air into the drain—be careful not to use too much force or you might disconnect the tube. Finally, take an old phone charger cable, strip out the thin copper wire inside, and slowly feed it into the pipe, twisting it a few times to pull out the debris. After unclogging, pour half a bottle of mineral water to test the flow rate. It's recommended to clean it every three months, especially for cars parked under trees—be more diligent with those.

My old Focus had a roof leak during heavy rain last year, and after some troubleshooting, I found that the end of the drain pipe was completely clogged with sand. The process wasn’t too difficult: open the sunroof, locate the coin-sized drain holes in the corners of the rails. Cut a thin straw from a convenience store at an angle, attach it to a household vacuum cleaner in reverse (remember to switch to blower mode). The key is to pinch the connection between the hose and the vacuum to prevent air leaks—once cleared, you’ll see water dripping near the tire mudguard. For routine prevention, regularly clean the drain mesh with cotton swabs, and never use a wire to poke forcefully, as puncturing the rubber tube would be troublesome.

This requires both courage and meticulousness. Prepare a spray bottle, fine fishing line, and WD-40. First, spray WD-40 into the drain to dissolve grease and sludge. After ten minutes, tie a small piece of cotton pad to the end of the fishing line and slowly thread it through the pipe like a needle. If you encounter resistance, pull it back and forth—the cotton will bring out moss and sediment. Remember, don't use a beverage bottle to pour water during testing; the flow is too fast to see results. Using a dropper to drip slowly is more accurate. Finally, apply some Vaseline to the rails to prevent rust—it saves you over 200 bucks compared to going to a repair shop.

Here's a pro tip from an experienced mechanic: Remove the interior trim panel in the passenger footwell (just three screws) to locate the white plastic T-joint. This spot tends to accumulate leaves - simply release the clip and clean with tweezers. For the middle section of the pipe, use a shower hose connected to tap water for flushing, adjusting the water flow to a pulsating rhythm for best results. To completely solve the issue, consider spending about 20 yuan to replace the aged, hardened rubber elbow, as OEM pipes typically become brittle and crack after approximately five years.


