What Causes Windshield Noise? And What To Do About It

Have you ever heard a whistling, popping, or rattling sound from your car’s windshield? Do you know what causes it?

Well, there are multiple causes for the noise. We’ll examine all four main causes in more detail below. Before we do, though, in brief:

Windshield noise can be caused if there is a chip or crack, the windshield seal is loose, there are stress cracks in the edges, or the windshield is installed improperly. Sometimes a windshield can be repaired but larger cracks mean a new windshield needs fitting.

Badly Fitted Windshield

You hear a noise from the windshield, most probably when there is a gap between the windshield and the car’s body. This gap causes air to escape air to enter or leave the car cabin.

This usually happens when you’ve recently replaced your windshield – but not always – and the technician has not installed it properly.

If your windshield is older and has been in place for more than a few months, the noise you hear may result from an accident that has disturbed the windshield’s position. Even the slightest bump at the front of your car can affect the dynamics of the chassis and result in the windshield being misaligned.

Driving with an ill-fitting windshield is dangerous; it must be fixed as early as possible.

It’s difficult to know whether air is escaping or being sucked into the car. This depends on the difference between the outside and inside air pressure. Many factors will affect the air pressure difference. These include how fast the car is traveling, whether there is a window or sunroof open, whether the car blower is on etc.

In reality, air leaking out or entering your car will make the same noise regardless.

Stress Cracks

Windshields become weak over time and develop minor cracks. One of the causes is the ever-changing temperature differences it is subjected to.

Many substances expand as they warm and glass is no exception. It may only be a millimeter, but that can cause cracks. Older windshields that have been through hundreds of heating and cooling cycles are more prone to this.

If you park a car for several hours in the sun and suddenly turn on the air conditioning, it may weaken the glass. These cracks may seem minor, but at high speeds, the air crossing through these produces whistling sounds.

Sometimes at higher speeds, a crack noise is heard as the windshield is cooled more quickly as the car is driven.

Some cracks can be repaired using adhesives, but if the car is quite old, it is advised to replace the whole windscreen.

Loose Seal

A popping noise from the windshield is often the sign of a loose seal. Sometimes it’s very loud and can cause a moment of panic.

The windshield’s dimensions are slightly smaller than the recess in which the windshield sits when being fitted. The rubber seal keeps the windshield in place once the adhesive has set the windshield in place.

The seal serves two important purposes. Firstly, it connects the windshield to the car’s body without the need to use screws. Secondly, it prevents water and air from entering the car through the front screen.

The seal is made of rubber. But since rubber has a lifespan, it eventually becomes brittle. When that happens, parts of it break away or become less supple, making the seal loose. The loose seal can allow air and water to enter, causing noise when you drive.

Sometimes water collects near the seal and causes rusting of the recess where the windshield is housed. This causes a gap, and the gap creates noise.

An easy way to diagnose if the rubber seal is at fault is by touching it. It’ll feel hard and brittle when it gets old, and small pieces may even come off in your hand.

Removing the windshield and re-installing it with a seal will fix the problem. Only do this if you’re competent. If not, take your car to a car shop and let them do it for you.

Chip/Crack on Side of a Windshield

Sometimes, you may hear a rattling noise on the windshield. This happens when there is a chip or cracks on the side of the windshield. This crack extends to the edge of the screen, and as a result, the glass debris rattles around the seal of the windshield.

These cracks around the windshield’s edges should not be repaired using adhesives; they will crack out again. So, when the cracks are along the edges, you should replace the whole windshield.

How To Locate Windshield Gaps

As mentioned earlier, the cause of the noise is air leakage or air entering the car.

Sometimes, the windshield has no cracks, and it looks like there is no leakage.

To locate the leakage, some tests can be done

Wind Test

For the wind test, close all the windows and doors of the car. Turn off the AC and the radio.

Now, drive the car on a highway at the speed limit. You will hear a sharp whistling noise from the front. With no other traffic noise and a quiet cabin, you should be able to pinpoint on which side and whether the gap is at the top or bottom of the windshield.

Water or Shower Test

Next, this test will pinpoint the exact location of the leak. Shower the front screen with water. Make sure to keep the pressure of the water high. If you have one, a jet washer will create enough force to push water into gaps around the windshield.

Often, this will be enough to cause water to leak into the cabin but not always. If it doesn’t, water may still be present but less obvious. Run a tissue around the edge of the windshield. Any dampness will be transferred to the tissue. If that doesn’t work, then try the test below.

Soap Test

Sometimes the gap is too small that it is undetectable using a water test. For that, we can use a soap test. Mix water with soap, and apply it to the seal and suspected crack locations.

Close the windows and turn on the heater. Now, inspect the windshield from the outside. You will see soap bubbles forming exactly at the leakage point.

How Much Does It Cost To Replace a Windshield?

If the windscreen is cracked slightly, you can fix those small cracks using a windshield kit that costs around $10-30. Be careful, though. If unsure, get an expert to do it for you.

The cost of a new windshield varies from car to car and from model to model. On average, windshield replacement costs range from $200 to 400.