How to test a radiator cap ?
Most common causes for engine overheat is from radiator cap. Yes, this small item is often overlooked. Whereas, the radiator cap function is very important for the engine cooling system.
As we discussed in several post before about how does a radiator cap works? The radiator cap is used to maintain the cooling system pressure to remain the same at a constant level. If it fails, then the pressure will lost and the result is your engine will overheat.
To know how bad or good a radiator cap is, we have to test it with radiator pressure tester tool. The picture below is an example of radiator pressure tester tool that used to check the radiator cap.
So how do we perform a test for the radiator cap? Below are the steps for checking the radiator cap with the tester tool....
The first step to test a radiator cap is to remove the cap from radiator. But before you remove the cap from the radiator, you must be sure that the radiator or the engine cooling systems is in a cool condition.
Removing the radiator cap while the system in a hot temperature can be dangerous and can cause injury. So, for a safety reason, allow the cooling system to cooling down first before removing the cap.
After removing the cap, check the overall radiator cap condition such as rubber seal on the pressure valve and vacuum valve, spring condition on the pressure valve, and vacuum valve condition.
Inspect all items from damage. Cracked cap, rusty spring, or hardened rubber seal require replacement of the radiator cap. If you see any damage as we mentioned above, its better to replace the cap with the new one on the same specification.
Install the radiator cap onto the radiator pressure tester tool. Some tools need an adapter that looks like a radiator filler neck. Install the cap accuratelly and make sure it fits on the adapter.
Since there are several different sizes and shapes of radiator cap, select the adapter that is the same shape as the radiator filler neck on your specific vehicle.
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Pump the radiator pressure tester tool and see the gauge until the pressure value is the same as the value were stamped on the radiator cap.
If the pressure releases the pressure before reaching the correct pressure, or the cap does not hold pressure, try to remove the cap from the adapter, and reinstall it again on the adapter correctly. Pump the tester again and wait for one or two minutes to see the result of the test.
See the pointer movement of the gauge to determine the test results of the radiator cap. The following table are the results of the radiator cap inspection
If the radiator cap test was failed, change the radiator cap immediatelly with the new ones and be sure to select the raditaor cap wih the same specification (choose the same pressure were stamped on top of the cap)
As we discussed in several post before about how does a radiator cap works? The radiator cap is used to maintain the cooling system pressure to remain the same at a constant level. If it fails, then the pressure will lost and the result is your engine will overheat.
To know how bad or good a radiator cap is, we have to test it with radiator pressure tester tool. The picture below is an example of radiator pressure tester tool that used to check the radiator cap.
So how do we perform a test for the radiator cap? Below are the steps for checking the radiator cap with the tester tool....
1. Remove the cap from radiator
The first step to test a radiator cap is to remove the cap from radiator. But before you remove the cap from the radiator, you must be sure that the radiator or the engine cooling systems is in a cool condition.
Removing the radiator cap while the system in a hot temperature can be dangerous and can cause injury. So, for a safety reason, allow the cooling system to cooling down first before removing the cap.
After removing the cap, check the overall radiator cap condition such as rubber seal on the pressure valve and vacuum valve, spring condition on the pressure valve, and vacuum valve condition.
Inspect all items from damage. Cracked cap, rusty spring, or hardened rubber seal require replacement of the radiator cap. If you see any damage as we mentioned above, its better to replace the cap with the new one on the same specification.
2. Install the cap onto the radiator pressure tester tool
Install the radiator cap onto the radiator pressure tester tool. Some tools need an adapter that looks like a radiator filler neck. Install the cap accuratelly and make sure it fits on the adapter.
Since there are several different sizes and shapes of radiator cap, select the adapter that is the same shape as the radiator filler neck on your specific vehicle.
Read also:
3. Pump the radiator pressure tester tool
Pump the radiator pressure tester tool and see the gauge until the pressure value is the same as the value were stamped on the radiator cap.
If the pressure releases the pressure before reaching the correct pressure, or the cap does not hold pressure, try to remove the cap from the adapter, and reinstall it again on the adapter correctly. Pump the tester again and wait for one or two minutes to see the result of the test.
4. See the results from the gauge
See the pointer movement of the gauge to determine the test results of the radiator cap. The following table are the results of the radiator cap inspection
| No | Pointer gauge movement | Radiator cap condition |
|---|---|---|
| 1 | The pointer stand still and holds the pressure at the same pressure value for several minutes | Good |
| 2 | The pointer moving down and lost the pressure after several minutes | Bad |
| 3 | The pointer won't stand and the pressure are lost when pumping | Bad |
If the radiator cap test was failed, change the radiator cap immediatelly with the new ones and be sure to select the raditaor cap wih the same specification (choose the same pressure were stamped on top of the cap)