Water Leaking Into a Car
If you have water leaking into your car, you need to deal with it promptly because of the many serious problems it can cause. If water sits for too long in a car's carpet, mold can grow and cause bad smells. Other problems can include corrosion of pin connectors, computer failures, sensor failures, rust, and high humidity inside the car causing your windows to fog up.
Where Is the Water Coming From?
A wet carpet is not the only sign of water leaking in a car. If you have an idea of where the water is getting into the car, check for water marks, stains, or even signs of rust. Take a close look at connectors for corrosion and check brackets for rust spots; you will be amazed what you will find when you look for it. I have always said, "Mechanics' best tools are not found in their toolbox, they are found in their heads." Water leaks are hard to pinpoint, but once you find exactly where the water is coming in, you can access the problem spot and repair it.
Leaks from Outside the Car
The number one cause of a water leak in a car is the poor installation of a windshield. If you have had a windshield replaced recently, take a look at this possibility. I'm not trying to disrespect windshield replacement companies, it's just that some companies hire people who just don't care; they will cut out the old windshield and slap in the new one without proper preparation.
If a professional replaces the windshield, it will take a minimum of an hour. It takes time to remove the moldings, cut the windshield out, trim the old urethane so the new windshield sits flat, touch up any scratches in the paint from the removal process, prime the glass with a primer, and install a nice bead of new urethane.
If your "professional" replaced the glass in just 15 minutes, his or her work might be not just the cause of a water leak but a safety issue. In the event of a car crash, you could be thrown through an improperly installed windshield and severely injured. I am good friends with a guy who owns his own windshield repair company, and I see and hear the horror stories, so I write to you from experience.
Leaking Body Seams
Body seams are the second major cause of water leaking in your car. Seams that weren't properly sealed at the factory, or seams that were broken open by a car accident, will usually cause the mystery water leak. Finding the point of entry is worth the struggle.
Once you find the seam that is leaking, I recommend using on the problem area. This is the same sealer auto makers use in the factory to seal all seams in the body of the vehicle after they are welded. One reason I like to use this seam sealer is that it skims over in about 30 minutes, so you don't have to wait a long time between water tests. Nevertheless, if you can let the car sit overnight after sealing it, the sealer will adhere to the body seams completely, and you won't have a seam open again because of the body flexing before the sealer is completely dry. 3M Brushable Seam Sealer
Water-Testing Your Car for Leaks From the Outside
Finding the point of entry is the first step in keeping rainwater out of your car. This investigation is time-consuming, but something you can do yourself. You need to physically see where the water is coming into the car, not just where it is traveling along a panel or a seam. To test your car, pour water on it: start at a low point and work your way up to the roof. If you determine that water is leaking into the bottom of the windshield, there is no need to go any higher with the water test until after you've fixed this first low leak.
Leaks Into the Trunk
A foul, moldy smell in the trunk may result from water getting in around the taillights or the trunk lid. If you can identify these leaks you can get them fixed.
How to Check Sunroof Drains
Leaking Sunroof: Finding Clogged or Disconnected Sunroof Drains
Leaking Aftermarket Accessories
Poorly installed aftermarket accessories are another major cause of water leaking in your car. Anything from a sunroof to a roof rack system, if not installed properly with the right sealer, will cause a water leak in a car.
If you have a factory-installed sunroof, check the drains. Sunroofs leak! That's why a factory-installed sunroof has a built-in tray with four drains, one in each corner of the sunroof. Sometimes these drain tubes become disconnected or clogged and will cause water to leak into the car. Locating the drains and checking them for proper drainage can take some time because they are usually buried in fenders and body panels, but it's time well spent. A shortcut to locating the drains is to fill the sunroof tray with water and watch where it goes when it drains. It will usually spill out in the front and the rear of the rocker panels.
Leaks From the Inside of the Car
Some leaks into the passenger compartment happen when it hasn't even been raining; they involve fluids created by the car's cooling or heating systems.
Clogged Air Conditioner Drain
When air conditioners take humidity out of the air in the passenger compartment, they end up collecting a lot of water that has to drain out of the car. Water dripping out of the air conditioner drain onto the ground is totally normal; water dripping onto the floor of the car from the air conditioner is not. If you haven't had any rain, and you have water leaking onto the passenger's floor, check your air conditioner drain or evaporator drain; it may be clogged or disconnected. Debris gets sucked into the evaporator from outside and occasionally will clog the drain tube. A temporary quick fix for this problem is blowing compressed air into the drain tube located under the car, but eventually you will have to remove the evaporator and clean out the debris.
Leaking Heater Core
Another possible cause of wet carpet, especially in the front of the car, when it hasn't been raining, is a leak from the heater core. Car heaters circulate coolant through the dashboard area to heat the car, and if the heater core springs a leak, coolant can drip onto the floor.
Let's Share Information
I hope this has given you some insight on water leaks and a few ideas on where to start looking. If you have a question about water leaking in a car, leave it in the comment box below, and I will answer it ASAP.
Questions & Answers
How can I find where the water is coming in my car? A pool of water forms on the carpet in front and back well of my Nissan Micra. We have checked all the places mentioned.
You'll need to pull back the carpet where the water is pooling, dry the floor with a towel, then water test the vehicle with a hose on the roof in the area the water is seen. You'll need to have a flashlight and watch to see where the water is streaming in.
Before you start, inspect the interior of the vehicle by running your hand on the areas of carpet that go up the sides of the vehicle to see if you feel any wet carpet that isn't at floor level. If you come across an area that is wet higher then floor level, start by water testing in that area.
There is water in the back passenger floorboard when it rains. I have checked the seals on front and back doors. I also made sure that the windows were up all the way, and checked the trunk, but no luck. I’m stumped?
Have you checked the front passenger carpet? When it's raining, people use there defog mode on the windshield. This uses the AC to remove moisture from inside the passenger compartment. If the AC drain (located on the front passenger floor near the firewall) is clogged, it will leak onto the front floor and flow into the back. So check the front carpet as well, and let me know what you find, thanks.
My daughter has a 2008 Nissan rogue and has had it for ten months, just recently it has water in the driver's floorboard and the back passenger floorboard behind the driver's seat, how do I find out where the water is coming from?
You'll need to pull the carpet back and dry under it. Check the trunk for any water in the spare tire well or anywhere else in the trunk. If the trunk is dry, check under the dash with a flashlight for any trails of water leaking down against the firewall, also look for rust stains or areas of the carpet higher than the floor that is wet, if there is, water test it in that area.