Flush and Refill Coolant System Task

Click here to download the teacher resource for "Flush and Refill Coolant System Tank Task."

Course: Maintenance and Light Repair (MLR I) 

Task Length: 1 hour

Flush and Refill Coolant System

Task Description


Students will:

  • Read the linked materials
  • Watch the linked videos using guided notes
  • Record a video of themselves describing the steps and tools involved in flushing and refilling the coolant system. 

Safety Note: If possible, students should do this task with a vehicle, but ensure the students do so safely. Lifting the vehicle is not required for the purpose of the student video.

6.11 Inspect and test coolant; drain and recover coolant; flush and refill cooling system with recommended coolant; bleed air as required.

Overall Standard (6): Students will perform basic vehicle engine service and maintenance.

 Content Understandings

Extending Understandings

Upon successful completion of these tasks students will demonstrate the ability to:

  • Explain why the coolant needs to be changed.
  • Explain why the coolant system needs to be flushed.
  • Select the tools required.
  • Describe required safety precautions.
  • Describe the order of the steps to flush the coolant system and add new coolant.
  • Explain why the vehicle must cool each time before the coolant is drained.
  • Locate the radiator cap.
  • Locate the radiator drainage valve.
  • Tell where to place the drainage pan to catch the old coolant.
  • Explain why the vehicle heater is run during the flush process.
  • Describe how full the radiator should be when the process is complete.
  • Describe what is done with the old coolant.

To move students towards deeper understanding, they should be given opportunities to:

  • Explain why the choice of coolant is important.
  • Select how to know the proper concentration of coolant.
  • Explain why gloves are worn.
  • Describe what to do if a vehicle does not have a radiator drainage valve.
  • Explain why the engine is turned on during the flushing process.
  • Tell why the radiator cap and inside the radiator gets inspected.


Support Strategies

If students are struggling to access this task, additional supports and strategies could be employed as students are engaging with the task.

Key Terms

Sentence Frames

Scaffolded Questions

Pressure valve

The radiator cap also serves as the radiator__________ _________ to regulate the flow of coolant from the radiator to the reservoir.

What is the purpose of the reservoir? 

How does the radiator cap/pressure valve connect the radiator with the reservoir?

Instructional Resources

Material to read (see student/teacher guide below)

Prestone (2017, Nov 27). How to do a Coolant Flush https://www.holtsauto.com/prestone/news/how-to-do-a-coolant-flush/


Videos to watch (see note guide below)

Note: The videos have different model cars

AutoZone (2017, Apr 10). How to Flush and Fill Your Coolant System (Video) YouTube. https://www.youtube.com/watch?v=ojop4forGbc (7:45 minutes)

Ben Wojdayla (2012, Jun 1). How to Properly Flush Radiator Fluid (Video). YouTube. https://www.youtube.com/watch?v=ZvtUOaj2jAI (7 minutes)

Mr. Kistel (2013, Apr 30). How to Change Coolant: Flushing a Vehicle’s Cooling System (Video) YouTube. https://www.youtube.com/watch?v=32ChpsR_dfo (6 minutes)


Additional Resources

ChrisFix (2014, Dec 4). How to Check and Test Your Coolant/Antifreeze (Video). YouTube.

https://www.youtube.com/watch?v=mHTM3dvpD1M (9:30 minutes)

Student Resources

Click here to download the student resource for this task. 

Student Reading Guide

How to do a Coolant Flush


  1. What may happen if dirty coolant is not flushed from the vehicle?




  1. What is a sign of coolant that needs to be replaced?




  1. What are the benefits of flushing the coolant system?




  1. What safety precautions are required while flushing the coolant system of a vehicle?




  1. What tools and parts are needed?


Student Video Guide


  1. Make sure the engine is _________. Never work on a cooling system when the engine is still ________ or even warm. Coolant/antifreeze can be extremely hot, and will retain its heat for hours after the engine was last running.


  1. Open the _____________________. While you’ve got the radiator cap off, you can give the radiator a good once-over to check its condition. Look for signs of rust and corrosion that could be affecting the performance of the cooling system. You should also check the two hoses running from the radiator to the engine (feed and return) for any signs of damage or leaks.


  1. Place the ________________ beneath the radiator drainage valve. Make sure the container you choose is large enough to catch all the fluid which drains from the radiator and cooling system. Place it directly beneath the drainage valve, which is usually attached to the bottom of the radiator on the left or right-hand side. The valve should have a bolt at the end, which is often covered by a plastic top that can be easily removed with a screwdriver.


  1. Open the ___________________ to drain the coolant out. Wearing gloves, twist open the bolt on the valve (you may need to use a socket and ratchet, or a spanner). The coolant/antifreeze will begin to drain out. When the flow has reduced to a drip, tighten the drainage valve until you begin flushing, and safely store the old coolant/antifreeze until you recycle it.


  1. Close the drain valve so you can flush the system. To ____________ with water and remove any leftover residue from the old coolant/antifreeze, top up the radiator with clean water, and replace the radiator cap. Then, start the engine and leave it running for 15 minutes. Wait for the engine to __________, then repeat the steps above to drain the water from the system.


  1. Add new coolant/antifreeze to the radiator to the fill line. Use the _____________________ suggested by the owner’s manual. Use premixed coolant or add distilled water in the proper amount.


  1. Now it’s time to add the new coolant/antifreeze to the __________________. Following the manufacturer’s instructions, fill the reservoir with fresh coolant/antifreeze to the fill line. When it’s filled, don’t replace the cap immediately. Instead, run the engine for 15 minutes with the interior heater turned on to maximum. This will bleed any air pockets from the radiator before you reseal the system with the pressure cap. After 15 minutes, switch off the engine, replace the cap, and you’re done. Remember to keep an eye on the level over the next week or so and top-up to the fill line if required.


  1. Antifreeze/coolant is ______________________.  It must be recycled properly.