How to Flush a Coolant System

Coolant being poured
  • 2-3 hours
  • Beginner
  • 50-75
What You'll Need
Adjustable wrench
Empty buckets
Flush kit
Garden hose
Cutting tool
Outdoor water supply

Flushing a coolant system is one area of engine maintenance that is very important. If your cooling system is faulty it could result in extreme heat in the radiator and could also hurt you when you open the cap. Knowing how to flush a coolant system is a task that is challenging and not too easy to complete. However, with the right tools and this guide you will be able to successfully flush your coolant system and have your car running once again. Here’s how you go about the job.

Step 1 – Accessibility

If you are planning to do any maintenance on your vehicle, it will be advisable to move it to a place where you have sufficient light and space to work.

Step 2 – Cool Engine

Your engine should be cool when you try to flush the coolant system. Do not try to work while the engine is still hot as there will be extreme pressure and heat and will injure you if you try opening the radiator cap.

Step 3 – Getting Started

Once the engine has cooled down you can start working to flush the coolant system.

Step 4 – Drain Valve

Locate the radiator drain which is normally at the bottom end of the radiator and drain the radiator. Collect the fluid into one of the buckets so that it does not drain off onto the floor.

Step 5 – Close the Drain Valve

Once all the fluid has drained out close the drain valve.

Step 6 – Flush Kit

Install the flush kit according to the instructions you received for that particular kit. Normally, you will need to slash the inlet hose that goes to the engine and install the “T” to the coolant line.

Step 7 – Connections

Once you have inserted the “T” section into the line that goes to the coolant, slip the hose onto the fitting and secure the clamps. Connect the garden hose to the fitting.

Step 8 – Divider

The divider must be placed on the radiator top where the coolant and water will pour out during the flushing process. Use a hose to direct the water to a bucket.

Step 9 – Flushing

Turn on the engine, make sure the heater is turned on high and open the water supply to the garden hose. The coolant will begin to circulate and come out through the diverter you placed on the radiator. Continue to allow the water to flow until you see clean water coming out.

Step 10 – Drain the Radiator

Switch off the engine and the garden hose. Open the drain valve on the radiator and drain it once again, use the bucket to collect the liquid. After the radiator has drained, close the drain valve.

Step 11 – Anti-Freeze

Pour the anti-freeze into the radiator and fill the radiator until you see coolant coming out of its neck. Place the radiator cap onto its place and screw it in place. The cap for the “T” fitting should also be screwed back again.

Step 12 – Finishing

Now you can take the vehicle for a test drive to check if everything is working fine.