Engines: Engine Cooling: Cooling system procedures
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Topic IntroductionHelp

Testing cooling system pressure

Summary
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. The objective of this procedure is to show you how to test a cooling system to confirm that it is without leaks and has the ability to hold the pressure specified by the manufacturer.

Part 1. Preparation and safety

Objective

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:

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

Points to note


Part 2: Step-by-step instruction

  1. 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.
  2. 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.
  3. 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.
  4. 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.