What Are Cowl Vents and How Do They Work?

Cowl vent by Monroe

Cowl vents are commonly found on cars, trucks, tractors, buses and other vehicles. Also known as dorade boxes, they are designed to facilitate airflow. You can find cowl vents in different sizes and styles, but they all allow air to enter or leave a space. What are cowl vents exactly, and how do they work?

What Are Cowl Vents?

Cowl vents are ventilation devices that allow air to enter or leave a space, such as an engine bay or cabin. Most vehicles have an engine bay. The engine bay is an enclosed space that houses the vehicle’s engine as well as other components. The hood for an engine bay often features a cowl vent.

Engine bays can get hot. Assuming it’s an enclosure for an internal combustion engine, the engine will produce hot exhaust gases. Some of the heat from these exhaust gases will transfer to the engine bay. A cowl vent, however, will help to reduce heat buildup. It will allow fresh air to enter the engine bay, thus protecting the engine bay from excessively hot temperatures.

How Cowl Vents Work

While available in different sizes and styles, all cowl vents feature an opening. You can see an example of a cowl vent in the photo above. The depicted cowl vent cover has a rectangular-shaped opening. Air can flow into or out of the cowl vent cover via this opening.

Most cowl vents feature a mesh material over the opening. This mesh material is designed to filter particulate matter. It will prevent dirt and other forms of debris from passing through the cowl vent. Air will still be able to enter the opening and pass through the cowl vent, but the mesh material will catch and prevent debris from passing through.

Installing Cowl Vents: What You Should Know

Cowl vents are easy to install. Since they are made of metal — zinc-plated stainless steel is a common material used in their construction — you can weld them in place. Welding will secure the cowl vent to the hood of an engine bay or cabin. Using a welding torch, you can weld a cowl vent onto a metal hood.

Rather than welding them, you may want to install cowl vents using rivets or bolts. You can rivet them in place, or you can connect them to the hood with a set of bolts. There are multiple ways to install cowl vents, some of which include welding, riveting and bolting.

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