Car radiator cap

How to detect the radiator cap failure

The first step of the part diagnosis is visual inspection. You need to inspect the cap and make sure it is intact. Any mechanical damage (scratches, cracks, rust) shows that it is time for the cap replacement. Next, you have to examine the spring. For this purpose you need to compress it. If the spring compresses too easily, it has already reached its service life limit and is subject to replacement.

Inspect the pressure relief valves: if the part is in good working order, they should raise effortlessly and return to their initial position under the action of the spring. You can check the cap tightness on the test bench. It must sustain the nominal pressure specified by the manufacturer.

You may identify that the radiator cap needs diagnosis by the following symptoms:

• engine overheating;
• increased coolant consumption, indicating its leakage.

Causes of the radiator cap failure

Sometimes the coolant cap breaks down due to the end of its service life. Since, during its use, the part is constantly exposed to high pressure, you should use only high-quality spare parts, manufacturers of which guarantee compliance with standards: reliable spring and seal are used, the component is checked for leaks.

Another cause of the radiator cap breakdown may be its improper position. If the cap does not fit tightly to the neck, it will let air in, consequently, the coolant will boil. In such a case, it is reasonable to inspect the radiator itself: perhaps the problem lies in the neck deformation or the expansion tank incorrect mounting.

Repair and replacement of the radiator cap

As a rule, the part repair is not performed. You can replace the radiator cap on your own or contact a service station. The replacement procedure is very easy:

1. You must wait till the engine has fully cooled down.
2. Unscrew the faulty cap and screw a new one in its place. You have to screw it in tightly so that the cap does not get unscrewed during the car use due to the radiator vibration.