The Purpose of the Radiator Cap and Bad Symptoms

Last Updated on November 24, 2019 by themechanic

In this post, I will share information according to the important part in the cooling systems, the part is Radiator Cap. So, I will explain basic purpose of radiator cap and 5 common failure symptoms.

Basic Purpose

The radiator cap of a vehicle is commonly referred to as a radiator pressure cap. The reason is that the job of the radiator cap is to keep coolant stored and pressurized in the radiator system. Don’t forget that 16 psi (pounds per square inch of pressure) exists inside the radiator. The radiator cap is what manages this pressure and keeps it consistent. If the radiator cap were to get damaged or worn out, then it may not be able to contain the coolant any longer. This means there will be less coolant available to prevent the engine from overheating. Meanwhile, your radiator will become damaged too. That is why you need to ensure that your radiator cap is always strong and functional.

5 Bad Symptoms

The question is, how will you know when your radiator cap goes bad? Are there any signs or symptoms you can notice? Fortunately, the symptoms of a bad radiator cap will be more than obvious. You just need to take them seriously as you notice them and recognize why they are occurring. Then you can do something about it before it causes too much damage to your radiator or engine.

Below are the top 5 symptoms of a bad radiator cap.

1) Coolant Leak

A bad radiator cap can cause coolant fluid to leak out of the radiator. For instance, let’s say the radiator cap cannot be taken off because it is stuck. That would mean the coolant fluid is stuck inside of the radiator. As a result, the pressure inside keeps building until the hose cannot contain it anymore. Then, the hose breaks open and leaks coolant fluid. Alternatively, there may be holes in the radiator itself too. Check both areas to see where the leak is coming from.

2) The Collapse of the Radiator Hose

If your radiator hose actually collapses, then you have a bad radiator cap for sure. This would be a continuation of the previous symptom if you failed to do something about it right away. A collapsed radiator hose will require you to replace it completely rather than merely repair it. You’ll also need to replace your radiator cap too. Don’t postpone this because your engine won’t survive very long without proper cooling.

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3) Reservoir Overflows

When coolant expands in the radiator, it flows into the reservoir tank. Normally, the pressure created within the radiator will release the radiator cap. This is how coolant is transferred to the overflow tank. But if your radiator cap is acting faulty in some way, then an abundance of coolant may flow fast to the overflow tank. Once this happens, the reservoir will start to boil over.

4) Air Pockets in the System

Sometimes your radiator cap may be in good condition, but not sealed the right way on the radiator. If the cap is too loose, then it won’t stop air from getting into the cooling system. You certainly don’t want this to happen because your radiator hoses, heater core, and thermostat will start to form air pockets in them. From there, the temperature of your engine may get hotter than normal.

5) Overheated Engine

Continuing on from the previous symptom listed, you may experience an overheated engine because the cooling temperature cannot be maintained anymore once you have air pockets in the system. The last thing that you’ll want to have is an overheated engine because its components will get severely damaged. Then you’re looking at paying thousands of dollars in repair or replacement expenses. It is so much easier to just replace or repair the radiator cap when it is immediately showing signs of problems.

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