Engines: Engine Cooling: Cooling system procedures
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Topic IntroductionHelp

Draining & refilling coolant

Summary
The objective of this procedure is to show you how to drain cooling system and refill with correct mixture of engine coolant. Some vehicles have drain plugs on the side of the engine block. The shop service manual will tell you if these need to be opened when draining the coolant.

Part 1. Preparation and safety

Objective

Engine coolant

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

Draining coolant through drain plug


Part 2: Step-by-step instruction

  1. Locate drain plug
    Locate the cooling system drain plug or valve on the bottom tank of the radiator. Place a clean drain pan large enough to contain all the coolant underneath the drain valve.
  2. Drain radiator
    Carefully remove the radiator pressure cap. This will allow air into the cooling system so that it can drain quickly and completely. Open the drain valve so that the coolant can drain into the pan below. When all the coolant has drained out, close the drain valve.
  3. Refill coolant system
    Check the shop service manual for the capacity of the system, and the recommended type and mixture of coolant for the operating conditions of the vehicle. Measure the recommended amount of coolant and using a funnel pour it in through the top of the radiator.
  4. Start engine and verify
    Air can be trapped in the cooling system, so leave the radiator cap off to allow it to escape, and run the engine for a few minutes to allow the coolant to circulate and get rid of trapped air. Then replace the radiator cap and bring the engine up to operating temperature. Check the coolant level in the reservoir and top it up to the high or hot engine mark.
  5. Dispose of waste
    Antifreeze is toxic, so dispose of the waste coolant carefully and in an environmentally recommended way.