a photo of a windshield with rain on it

Windshield seal repair

On the Road 3 min read

A few drops of water may not seem like a big deal if you can easily wipe them up, but a leak around your windshield is nothing to ignore. A windshield leak left untreated can lead to extensive water damage to your car. It may even affect the resale value of your car. However, you can repair many leaks inexpensively in a few simple steps.

We asked Richard Reina, product training director, and automotive enthusiast at CARiD, an online auto parts store, how to fix a leaking windshield. We also asked what causes leaks, and how to identify signs your windshield may be leaking.

Why do windshields leak?

The good news is that windshields leak a lot less than they used to due to advancements in manufacturing techniques. The bad news is that leaks sometimes occur when the seal between the glass and the vehicle’s body is bad. There are several reasons why seals get impaired. According to Reina, exposure to extreme temperatures, collisions, or failure by the factory to use enough urethane glue are common culprits.

Symptoms of a windshield leaking

If you expect to see water cascading into the driver’s seat when your windshield is leaking, think again. Signs of a windshield leak can be much more subtle than that and may go undetected. “Water leaks can be tricky to diagnose,” Reina says. If you notice any of the following, it could be a sign that water is coming in where it shouldn’t be.

  • Condensation
  • Musty smell
  • Mold
  • Staining
  • Rust inside the car

How to test the windshield for leaks

If you’ve got water coming in where it shouldn’t be, it’s crucial to find out the source of the leak. Here are two ways to test your windshield for leaks. But before you get started, Reina recommends making sure your car’s interior is dry.

Spray the vehicle

Get a friend or family member to sit inside your car while you spray the outside. Spray one area of the vehicle at a time and have the person inside the car watch for signs of water leakage. If there’s no sign of water inside the car, Reina recommends partially disassembling the interior. “Seats come out of a car fairly easily. Carpet can be picked up,” he says. When you remove those items, you might see water traveling from one part of the car to the other.

Lather the vehicle

Dab some detergent around the perimeter of the windshield. Spray the windshield lightly. You don’t want to wash all the soap away. Turn on the defroster inside the car to blow air against the windshield. “If you have a leak, and you’re lucky, you may see the soap bubbles start to enlarge or start to move outside the car,” Reina says.

Risks of not repairing a leaky windshield

Water from any source, whether it’s a leaky windshield or flood damage to your car, can lead to more severe issues, including:

If you leave water on the vehicle’s body, it’ll start to rust and corrode. Reina says this is true even of newer cars with corrosion protection. Mold may also build up in the car and cause health issues such as a stuffy nose, red and itchy eyes, or wheezing.

If the leak causes extensive damage, the value of your car will likely depreciate. Many vehicle parts are computerized today. “If water gets into those computers, you’re going to start to have some warning lights come up on the dashboard or [there may be] some things…not functioning as they should,” Reina says.

How to fix the seal around a windshield

Do-it-yourself (DIY) windshield seal repair is possible. Before you get started, it’s crucial to pinpoint the exact location of the leak, so that you can put the sealant in the correct place. You would do well to use a sealant designed explicitly for windshield repair. “Do not use household-based silicone. Do not use super glue that you used to fix your child’s toy,” Reina cautions. Once you’ve located the leak, you can do the following:

  1. Put masking tape on the glass where you’re working so if you slip or drop something, it will protect the glass.
  2. If there’s decorative molding around the windshield, lift it or remove it altogether, depending on the vehicle. Not all windshields have molding, so you may be able to skip this step.
  3.  Apply the sealant into the joint between the windshield glass and the body of the car — or as close to the joint as you can get it. “If you’re going to use a tool to apply the glue, use wood or plastic, not metal,” says Reina.
  4. Wait for the sealant to dry.
  5. Remove the masking tape.
  6. Put the molding back into place.

How much does windshield seal repair cost?

If you’re planning to fix the seal yourself, all you need to pay is the cost of the sealant, which you can get for around $10 online or at an auto parts store.

Some leaks may require the entire windshield removed and set with a new seal. This is a much more involved endeavor that requires an expert. Contact an auto glass specialist shop to get an estimate for the work. You can probably even find one that provides a mobile service that can come to you to repair. After learning about windshield seal repair, discover how to replace windshield wipers.

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