How to Fix Car Tail Lights: A DIY Guide to Sealing Leaks

Discovering water droplets inside your car’s taillights after a car wash or rain can be frustrating. It’s a common issue, and thankfully, often fixable at home without extensive tools or expertise. This guide will walk you through a simple and effective method to seal those pesky leaks in your car’s tail lights, focusing on a straightforward DIY approach.

Understanding Why Water Gets into Your Tail Lights

Many car owners mistakenly believe water inside taillights is just “condensation.” However, true condensation is rare in sealed light units. More often, the moisture you see is actually water entering from outside due to a compromised seal. In many car models, particularly those with taillights that have a separate red lens and housing, a common culprit is a small gap that develops along the top edge seam of the taillight.

This gap isn’t usually due to a faulty gasket that seals the entire taillight assembly to the car body. If you’re not finding water in your trunk, the main gasket is likely doing its job correctly. Instead, the issue often lies within the taillight housing itself. Over time, the plastic lens and housing of the taillight expand and contract with temperature changes. This normal process can, unfortunately, create a hairline gap along the top seam where the red lens meets the black housing. Because of the taillight’s design, this top seam is often exposed to the elements, allowing rainwater or car wash spray to seep directly into the light unit.

DIY Solution: Sealing the Tail Light Seam with Silicone

The good news is that fixing this type of taillight leak is usually a simple matter of sealing that exposed top seam. Here’s how you can do it yourself using silicone sealant:

Step-by-Step Guide:

1. Inspect Your Tail Lights: Carefully examine the top edge of your taillights from outside the car. Look for an uneven or visible gap along the seam where the red lens meets the taillight housing. This is most likely to occur on the top edge of the left and right taillights, but not typically the center section if your car has one.

2. Ensure Dry Conditions: It’s crucial to perform this repair when your taillights are completely dry. If there’s moisture inside, wait for a dry day or use a hairdryer on a low setting (from a safe distance) to help evaporate the water. You don’t want to trap moisture inside when you seal it.

3. Apply Silicone Sealant: Using a tube of clear silicone sealant, apply a thin, consistent bead along the top seam gap you identified. Focus on filling the gap where the lens and housing meet.

4. Smooth the Sealant: Immediately after applying the silicone, use your finger or a gloved finger to smooth the bead of sealant and press it flush into the gap. This will create a neat, water-tight seal. Don’t worry if you get a little silicone on the lens itself; you can easily wipe it away while it’s still wet.

5. Clean Up Excess (If Needed): If you have any excess silicone smeared on the taillight lens, wipe it off with a damp cloth or paper towel before it dries. Silicone is easiest to clean up when wet.

6. Allow to Cure: Let the silicone sealant cure completely according to the manufacturer’s instructions on the product label. This usually takes a few hours. Avoid washing your car or exposing the taillights to heavy rain during the curing time.

Optional Alternative: Drilling for Drainage (Use with Caution)

In more persistent cases, or if you prefer an alternative approach, some car owners have reported success with drilling small drainage holes.

• How it works: Drilling tiny holes (no larger than 1/8 inch) along the bottom edge of the taillight housing, in an inconspicuous location, can allow trapped moisture to escape and promote air circulation to dry out the inside.

• Important Note: This method should be used cautiously and is generally less recommended than sealing. Drilling can introduce new points of potential water entry if not done carefully. It’s also a permanent modification to your taillight.

• If you choose to drill: Ensure the taillight is dry first. Drill very small holes and only on the bottom edge, where they are least visible and less exposed to direct water spray.

Conclusion: Keep Your Tail Lights Clear

Dealing with water in your tail lights doesn’t have to be a major headache. By understanding the common cause – a gap in the top seam – and following this simple silicone sealing method, you can effectively fix the problem yourself. Regularly inspecting your taillights for gaps and addressing them promptly can prevent moisture buildup and keep your car looking its best and your lights functioning properly.