What does the radiator cap do?

What happens if your radiator cap fails? Well, a lot of things…

Radiator caps are an essential part of the cooling system and without them, your car wouldn’t function properly.

The radiator cap helps raise the boiling point of coolant, prevents air from entering the system and ensures the pressurised cooling system in your car runs smoothly. Pressurised systems are commonplace in modern vehicles and are necessary for them to run at higher temperatures. A radiator cap provides the much-needed seal for a pressured system, ensuring that coolant doesn’t boil over. Especially high performance vehicles or modified engines that require extra cooling, which is where higher pressures and therefore higher boiling points come into play.

So what happens if your radiator cap goes kaput? Read on to find out.

Natrad’s team of highly experienced technicians can provide helpful advice about your cooling system. From specialist repair and maintenance services to quality product recommendations, Natrad has your back. 

Signs & Symptoms

There are a few ways to tell if your cap might be on the way out. Some signs may indicative of other issues not related to your cap, so it’s important to check before diagnosing it as the culprit.

Key factors may include:

  1. Leaking coolant: caused by worn, stuck or damaged cap, leading to a build up in pressure. End result is a loss of coolant.
  2. Burst or collapsed radiator hoses: bursting could be due to build up in pressure or -when the vacuum isn’t released properly, causing collapse during the cooling down period.
  3. Overheating at lower than usual temperatures: this could be due to loss of coolant which will no longer be able to circulate and dissipate heat through the radiator.  Another reason could be air that has entered the system.
  4. Overflowing reservoir: normally coolant goes into the overflow tank as it expands, to release extra pressure.  If you have a bad radiator cap it may be released too quickly and cause an overflow (ironic given it’s name, we know).
  5. Inefficient cooling: a more subtle sign that something is wrong. Generally caused by ineffective sealing and could eventually lead to overheating.

If you notice any of these signs, Natrad can inspect your cooling system and diagnose problems and supply you with expert advice on what to do next. 

Effects on your cooling system

Without the cap, modern cooling systems wouldn’t be able to perform as they do today. If the cap fails, you could be facing some pretty hefty trouble.

Most of the signs and symptoms above lead to a few key problems:

  • Loss of coolant, leading to overheating
  • Overheating and breaking down
  • Damage to cooling system components
  • Part failure in extreme cases (e.g. radiator)

Checking your cap

Now that you know what a faulty radiator cap may cause, it’s time to inspect. Safety first when working with high pressure and temperature: do not open your radiator when the engine is still hot, this may result in severe burns and injuries. 

Some reasons your cap may have failed could be wear to parts like the seal or gasket. Alternatively, it may have received damage somehow, such as being corroded or crusted with residue.

You can see this sort of damage visibly, but you might have to look a little closer to see cracks or breakage in the seal or gasket.

So what do you do now? Natrad has a large range of quality replacement parts that may suit your vehicle. From radiator caps to radiators, we’ve got the lot. 

Choosing a replacement

If the radiator cap has indeed failed, you’ll be needing a new one. It’s important to choose the right cap as the pressure will be individual to your system. A good way to ensure you have the right cap is to see what pressure rating your previous one had, or check in your owner’s manual for manufacturer specifications.

Typically you won’t need to replace a radiator cap very often, but it’s recommended you do so every 5 years to prevent issues from popping up.

Ready to choose? Nip into Natrad for expert advise and quality parts for your cooling system.