5 Conventional Signs Of Defective Radiator Cap

A radiator cap is more important than most people think. We often overlooked it as being a cause of engine overheating. A radiator cap looks simple but, is critical for a property operating cooling system. Engine overheating is a result and loss of coolant or major engine damage. So, pressurized cooling systems help prevent overheating and coolant loss.

As the engine warms up and the coolant expands it becomes pressurized. The caps pressure relief valve allows pressure to build up to a specified level, then lets excess pressure escape.

Always check the cap during routine maintenance. Never remove the cap when the engine is hot. With the engine off, place a rag over the cap and remove it. Turn it counterclockwise about 1/4-turn until it reaches the safety stop. Allow all pressure to vent before removing the cap by pressing down and turning it counter-clockwise.'

There are a few signs that will let you know if you have a faulty cap:

1) Leaking Coolant

If the radiator cap is stuck, fluid cannot get released. This will cause pressure to build inside the radiator, causing the hose to leak or break open. If you notice coolant near the radiator or the radiator cap, then you have leaky coolant. Check to see if the radiator has holes in it or if the cap looks worn or damaged. If so, then replace the cap.

2) Overflowing Reservoir

Coolant goes into the reservoir tank as it expands. The cap is released by the pressure and the coolant is sent toward the overflow tank. If you have a bad cap, the coolant will get released too quickly and cause the reservoir to boil over.

3) Radiator Hose Collapses

You may have a bad cap if the radiator hose collapses. The vacuum won’t be released properly and it will cause the radiator hose to collapse during the cooling down period. If this happens, inspect the cap to see if there is any damage. If there is, replace it immediately.

4) Air Inside The Cooling System

When your cap does not seal properly, air will get inside the cooling system. This will cause air pockets to get inside the heater core, thermostat, and radiator hoses. As a result, the engine will start to overheat because it cannot sustain a consistent temperature.

5) Overheated Engine

Leaky coolant or air in the cooling system can lead to an overheated engine. If you notice your engine getting too hot, don’t look under the hood unless you've turned the engine off. That way, the engine can remain cool as you check it out. If there is coolant near the radiator cap, there could be damage to the pressure cap. Check for that and replace it as needed.