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Choosing the right radiator cap can make a big difference

Not all radiator caps are the same. There are many differences between radiator caps, like features, shapes and sizes, and picking the right one for your vehicle is very important.

Are you noticing signs that your radiator cap is going screwy? (pun intended). A malfunctioning cap may seem harmless, but it can cause plenty of damage to your engine. You may notice:

    • leaking coolant
    • burst or collapsed radiator hoses
    • overheating at lower than usual temperatures

And that’s only a few of the problems that might ensue. So, what do you do now? We’ve put together the following guide with everything you need to know about choosing the right radiator cap.

Our team at Natrad are Australia’s best and most trusted auto cooling specialists. We can help with parts and servicing for air conditioners, radiators, and all your vehicle cooling needs. Check out our wide range of coolant caps online.

Radiator caps for pressurised cooling systems

As of the past 20 years, a pressurised cooling system has become commonplace in modern vehicles. Modern engines generally use higher pressure cooling systems, which therefore require effective sealing.

A failure to do so would result in some pretty sticky situations such as:

      • inefficient cooling
      • loss of coolant
      • overheating

Pressurising the system raises the boiling point of coolant, so in extreme conditions, this creates a buffer by allowing it to run at higher temperatures.

Doing this prevents damage to the car, engine overheating and helps keep the system running smoothly. It also means that manufacturers can build engines with higher operating temperatures, which is especially common in performance vehicles. The radiator cap is a vital part of this process.

What is the function of a radiator cap?

The seal provided by the cap ensures there is constant pressure and secures control when it increases as the coolant heats up and expands.

Radiator caps can come in all shapes and sizes unique to your car’s radiator. Different vehicles have different systems and therefore work with individual pressures. Ensuring it all works smoothly comes down to this one little piece of the puzzle.

The cap also has a few other jobs, like preventing air from entering the system. If air enters the system, it can result in temperature spikes, overheating and cracking or warping in any part of the engine where the air is trapped.

Finally, the cap allows coolant to go to the expansion recovery tank when it gets hot, expands and pressures increase. Once the system cools, the coolant returns from the recovery tank. A malfunctioning radiator cap may cause the engine to overheat at lower temperatures or prevent the coolant from returning to the engine.

How to read pressure grading on your radiator cap

A radiator cap will have two pressure measurements on it, psi and kPa. Psi measures pounce-force per square inch and kPa stands for kiloPascals. They are both used to calculate pressure and depend on whether the system uses imperial or metric units of measurement.

Most caps are designed from 4psi (30kPa) to 30psi (205kPa), with the higher ratings typically found in performance or industrial applications. When choosing a radiator cap, it’s important you stick with the specified pressure for your system, as each additional pound above this increases the boiling point by 1.4°C.

Different seal types in radiator caps

A lot of cooling systems have a coolant recovery system, where the coolant flows to and from the expansion tank. These systems require a cap with a double seal to maintain integrity.

Double seal caps can also be used on non-recovery systems, whereas non-recovery systems typically have a single seal cap and cannot be used elsewhere.

What should you look for in a new radiator cap?

To ensure you have the right cap for your vehicle, it’s always a good idea to take a look at what you already have. From here, you can determine the correct shape, size, pressure grading and seal type. Your vehicle’s manual can also tell you the required specifications that your car will need.

Some caps have safety leavers on them, usually for performance and mining applications. The lever needs to be lifted prior to opening the cap, which helps prevent scaling and burns.

At Natrad, we have a variety of high quality radiator caps for sale. Whether you’re looking for a passenger car, commercial vehicle or industrial and earth moving applications, Natrad has a radiator cap suited to you. From a range of globally recognised brands like Denso, Tridon, Adrad and Mahle, there’s no compromising on quality. Speak to a cooling specialist at your local workshop today.