What Are the Symptoms of a Faulty Radiator Cap?

The radiator cap is a critical component of your engine’s cooling system as it has the twin responsibilities of storing coolant and ensuring the necessary pressure of the cooling system is maintained.

The pressure inside the radiator is sixteen pounds psi (per square inch). The radiator cap is designed to ensure that this pressure is always maintained to prevent overheating. If your car overheats, the radiator can sustain damage. This can have a cascading effect on other components of the cooling system and the engine.

4 Functions of the Radiator Cap

The radiator cap has four major functions. These include the following:

  • It helps in sealing the cooling system (job of the main seal).
  • It helps in keeping the cooling system pressurized while also increasing the boiling point of the coolant liquid.
  • It helps in ensuring that the excess pressure and coolant expansion effectively get transferred to the expansion reservoir (job of the pressure seal).
  • It helps in enabling the coolant liquid to flow to the radiator once the engine has cooled down sufficiently (job of the return seal).

Anytime the functions above are hampered or disrupted, it can lead to damage of the cooling system and an overheating engine. For this reason, it’s critical to ensure that your radiator cap is always in top working condition.

5 Commonly Overlooked Symptoms of a Faulty Radiator Cap

If the radiator cap is faulty, it will not be able to seal the cooling system. This will impact its ability to keep the radiator pressurized.

To know if your radiator cap is damaged or faulty, consider these five commonly overlooked symptoms.

Leaking Coolant

Any time the fluid inside the radiator does not get released, it can cause pressure inside the radiator to build up. When this happens, the hose can sustain damage and start to leak or even break.

One of the most common reasons this happens is if the radiator cap is stuck.

Watch out for the following signs of leaking coolant:

  • Coolant fluid near the radiator.
  • Coolant fluid near the radiator cap.
  • Damaged or worn out radiator cap.
  • Holes inside the radiator.

Overflowing Reservoir

As the coolant expands, it flows into the reservoir tank. The pressure leads to the radiator cap being released. When this happens, it enables the coolant to flow toward the overflow tank.

If, however, the radiator cap is damaged or faulty, the coolant might get released much faster – this can then cause the reservoir to boil over.

Overheated Engine

One of the most common causes for an overheated engine is leaking coolant. On top of this, air in the cooling system can also cause your car engine to become overheated. If you notice coolant fluid near the radiator cap, it is highly likely that the leaking coolant is what is causing your engine to get overheated.

A Word of Caution – If your car engine is overheated, NEVER pop the hood while the engine is still running. Once the engine has cooled down sufficiently, you can then go ahead and check for signs of leaking coolant near the radiator cap. 

Collapse of the Radiator Hose

A collapsed radiator hose is again a common sign that the radiator cap is faulty or damaged. If the vacuum does not get released by the radiator cap, the radiator hose might collapse when the cooling down happens.

Air Pockets Inside the Cooling System

Air can get inside your cooling system if the radiator cap cannot seal properly for any number of reasons. This can lead to the creation of air pockets inside the radiator hose, the heater core, or the thermostat – this also can lead to the engine overheating.

Final Checkpoints

A major aspect of preventive maintenance is checking the coolant level. While checking your coolant levels, make sure you check for leaks in the coolant or damage to the radiator cap as well.

If, however, for any reason, you are not comfortable checking the radiator cap yourself, but you suspect a faulty or damaged radiator cap based on the above-mentioned symptoms, have it checked by a professional car technician at the earliest. It might be necessary to replace the radiator cap to prevent damage to the cooling system and your engine.

Car Mechanics You Can Trust!

Do you suspect your radiator cap is damaged or faulty? If yes, we can help. Give Accurate Services a call today at 520-620-9129 or schedule an appointment online at your convenience!