Part 1. Preparation and safety
Objective
- Test a cooling system to confirm that it is without leaks and has the ability to hold the pressure specified by the manufacturer.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- When working around the cooling system, care must be taken particularly if the engine is at operating temperature, as the coolant may be hot enough to scald.
- Always allow the system to cool before removing the radiator cap.
- Do not remove a radiator cap from a hot cooling system.
- Always use extreme caution when removing the radiator cap. Releasing the pressure cap, on an engine at operating temperature, may cause the hot coolant to superheat.
- If you must remove the radiator cap from a hot system, wear protective gloves and eyewear and remove it slowly, to the first (safety) point, to prevent the pressure inside from erupting. If you don’t this could cause the scalding hot coolant to spill hot fluid over you or someone standing nearby.
- Make sure the engine is off when carrying out any visual inspection of the system or when you connect the tester. You may be required to run the engine after the tester has been installed and pressurized.
- When the engine is running, make sure that you keep any loose clothing away from rotating parts.
- When pressure testing a system, make sure you do not exceed the manufacturer’s maximum pressure.
- Have a qualified instructor show you the correct operation of the tester.
- Make sure that you understand and comply with all environmental and occupational health and safety standards for your workplace at all times. If you are unsure of what these are, ask your supervisor.
Points to note
- To test the cooling system for both internal and external leaks, a pressure tester is normally used. These are often referred to as cooling system testers or analyzers. There are a number of different analyzers used today. Make sure you are familiar with the system used in your workshop.
- If you need to replace a pressure cap, use only a cap with the correct recommended pressure. If a cap with a lower pressure rating is fitted, it will lower the boiling point of the coolant. Alternatively, a higher rated cap will increase the boiling point.
- Each 10 kPa (1.45 PSI) of cap-rated pressure changes the boiling point by 2°C (3.6°F). For example: A 90 kPa (13 PSI) radiator cap will increase the boiling point from 100°C (212°F) to 118°C (244°F). Similarly, a 100 kPa (14.5 PSI) radiator cap will raise the boiling point from 100°C (212°F) to 120°C (248°F).
- Pressure testing kits come with a number of adapters for various cooling systems. These adapters can be used to connect the tester to the radiator or to the radiator cap.
Part 2: Step-by-step instruction
- Inspect cooling system visually
Before pressure testing the system, visually inspect the system for any obvious signs of leaks or wear in the radiator core, radiator tanks, coolant and heater hoses, water pump, all accessible engine core plugs,
cooling fan, drive belt and radiator cap and seals.
- Check the operating instructions of the tester
Refer to the pressure tester’s manual for correct operation. The outside of the radiator cap should be marked with its operating pressure. When this pressure is reached, the pressure relief valve in the cap will allow a discharge into the overflow system.
- Test the radiator cap
Refer to the workshop manual or vehicle owner’s manual to check that the pressure cap fitted has the correct pressure rating for that cooling system. Attach the radiator cap to the tester with an adaptor and pump up the pressure on the radiator cap spring. The pressure should hold just below the relief pressure setting. If the pressure will not hold or it cannot reach this pressure, then replace it with a new cap of the correct type and recommendation.
- Test the cooling system
Before testing the integrity of the cooling system, top up the coolant level. Attach the cooling system tester to the radiator cap locator. Pump up the system pressure to slightly above the pressure recommended by the rating specified on the pressure relief cap.
Observe the pressure reading. If it remains steady and does not drop then the system is not leaking. However, if the pressure drops, look for the leak. If there is no visible external leak, then the leak is most probably internal.
If there are any visible leaks, or the pressure drops, refer you test results to your supervisor.
