How Radiator Pressure Caps Are Used

by | Mar 18, 2016 | Electrical

One of the most important components of your vehicle is the radiator. To ensure that your engine operates at the proper temperature, coolant is used to reduce the amount of heat generated by the engine. However, without a radiator to keep the coolant at the proper temperature, your car would overheat very rapidly. While the radiator itself is usually a simple air-cooled system, there are multiple parts that keep everything in check. The lynchpin of this device is the radiator cap, which is used to regulate the coolant inside. In modern cars, the cooling system is pressurized, meaning that the radiator cap must also maintain a higher level of pressure. There are several types of radiator cap, but today we will discuss radiator pressure caps, and how they can be beneficial to your car.

How a Radiator Pressure Cap Works
As we mentioned, your vehicle’s cooling system is usually pressurized, with most operating at about 15psi. The reason for this is to help draw coolant to the engine and the radiator, and then back to the coolant reservoir. In older cars, the coolant would be released on the ground after being used; thankfully, though, we don’t have that issue anymore.

One of the biggest problems of the cooling system is the fact that the coolant expands as it heats up. We all know that boiling water generates steam, so what happens to that steam in a closed system? Even though the coolant is held at a higher pressure to increase its boiling point, there are times that the pressure gets too high, and must be regulated. That is where the radiator pressure cap comes in.

Maintaining Pressure
If the pressure inside the system increases past the optimal level, the radiator pressure cap releases it into an overflow tank. This is done via a spring-loaded valve. The coolant sits in the overflow tank until the entire system has cooled down, when it is sucked back into the reservoir, also via the radiator pressure cap. As the pressure decreases due to the lower temperatures, another valve opens, allowing the coolant to pass back through to the reservoir.

Because different cars operate at different pressures, it’s imperative that you get a radiator pressure cap that works with your system. It may be tempting to “upgrade” with a higher level cap, but deviating from the manufacturer’s rating can cause damage to the system overall. Check with your local auto parts store about what kind of radiator pressure cap is right for your car.

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