Vehicle Windshield Stress Crack: Definition, Causes, Prevention & Repair

While we have various vehicles’ windshield/windscreen cracks, our focus on this topic will be Vehicle Windshield Stress Cracks. This has always been an unwanted phenomenon, especially in areas with hot climates like Africa.

Today, I shall be talking about the avoidable but difficult-to-repair stress crack. To understand this very well, I will list some cracks that can affect your vehicle’s windshield. Unfortunately, other cracks might be unavoidable, but stress cracks are 100% avoidable. Suffice it to say that stress cracks are also more common than other types.

Various types of Vehicles’ Windshield Cracks

• Bull’s eye/Half moon
  Circular ding, with a cone in the outer layer of glass. A half-moon crack is similar but not completely circular.
• Chip: Damage by a rock that causes a small piece of glass to break off the windshield.
• Floater crack: The floater crack is less common than an edge crack, which is caused by severe temperature changes (freezing temperatures) to stone breaks.

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What is a Vehicle Windshield Stress Crack?

In layman’s language, I will describe a stress crack as a crack that occurred in your vehicle without anything hitting the windshield. The image above is a good example of a vehicle with a stress crack.

Stress cracks will typically be a straight (or slightly bending) line with no sign of impact. A “pen test” is often used to determine if there is a stress crack.  To perform this test, you need to run a ballpoint pen along the crack, and if it dips anywhere, it is not a stress crack.

A wide range of temperatures has a direct effect on a chipped windshield. The metal in the frame of your car or truck can expand and contract at a different rate than the windshield glass. This places stress on the windshield frame, which cracks the glass further. That is because, with a stress crack, no glass comes off the windshield. Let me post at least two pictures of what a stress crack looks like

What Factors Cause a Vehicle Windshield Stress Crack?

1. A significant temperature variation is the most common cause of a windshield stress crack. For example, this can occur if your car has been sitting in the hot sun all day and then you blast the AC with all the windows wound up.
2. Furthermore, and still on the effect of significant temperature variations, If your car is parked in the sun for hours, please ensure you wind down the windows a bit. Don’t wind it down all the way if you suspect a break-in. Remember that pilferers can take advantage of this and make away with your valuables.  It will be the best practice if you park it where there are people who can help you watch over it). By doing this, you are preventing hot air from being trapped inside the car.
3. Another cause is; when a vehicle becomes overheated from sitting in the sun, and you start washing the car with cold water. This will eventually result in stress crack and subsequent damage to your paint job. Please warn those who wash your car about this. The car must cool off before washing. Do not wash in direct sunlight for whatever reasons.
4. The opposite example would be a freezing car suddenly being exposed to heat. This is why, in the winter, ice should be scrapped or melted off the windshield with cold water, but never with warm or hot water.

Can a Vehicle Windshield Stress Crack be Repaired?

The answer is yes and no. If the mark /crack is not more than 6 inches long, it is repairable, but if it is larger, it is not a candidate for repair. I have personally repaired between 2 two 4 inches long stress cracks using some resins bought on Amazon.

Stress cracks typically start from the edge of the windshield, and they can quickly become quite large. These two factors combine to make most stress cracks irreparable.

In general, if a windshield crack emanates from the edge of the windshield (as is common with stress cracks), is in the driver’s line of vision, exceeds a certain length, or is contaminated with debris, the crack is irreparable.

How to repair a Windshield Stress Crack

The windshield repair process involves drilling into a crack and filling it with a resin that hardens within the crack. The goal is to stabilize the crack and prevent it from spreading. This is similar to having a dentist fill a cavity in your tooth.

However, even if a crack is not in the driver’s line of vision, if it’s near the edge of the glass, it may not be repairable because the suction device used to repair cracks needs sufficient space and a good seal.

In a situation I witnessed(you can confirm this from my pictures above), local glass cutters tried to stop my stress crack. What they did was to put a deep mark and the end of the crack. Unfortunately, they ended up making it worse. I would have been luckier had I acted early enough. So, please be warned stress crack is difficult to repair when not detected early enough.

How can I Prevent a Future Windshield Stress Crack?

• By parking your car in a garage or other temperature-controlled environment(I mean a shaded garage). Leaving your car out in the sun or the cold tends to make the edges of the glass more brittle.
• Secondly, If you notice a crack or ding in your windshield, have it looked at immediately! The longer you wait, the more damage you are in for. I can personally help you with a cheap repair if detected early enough.
• If you cannot help but park your can in the hot sun all day, please wind the windows down a bit to allow free passage of hot air.
• Do not wash your car in direct sunlight, and do not wash your car immediately after leaving the sun
• Another foolproof method is to buy a car sunshade or a multipurpose breathable car cover.  I mean an actual car umbrella that will shut out the sun, snow, dust, and rain without resulting in any damage to your paint job or windshield. See some examples below:

YITAMOTOR 8 Layers 3XL Car Cover Aluminum Outdoor Seamless Waterproof Rain Sun UV Dust Wind Resistant

Car Windshield Sunshade Jumbo (63″ x 35″) for Car Truck SUV Minivan – UV Protector Shields Auto & Keeps Vehicle Cooler

FINAL Note

Original car covers are more expensive than car shades. However, their functions also differ.  To prevent a Vehicle’s Windshield Stress Crack from occurring, you are not advised to use sunshades alone as it tends to protect more of the interior than the exterior.

When using a sunshade, you must wind down your window a bit.  As for car cover, you can use it alone as full-time protection against UV rays, dust, sun, and rain.