How To Flush Your Motorcycle Coolant

The cooling system in your bike is rather important because, you know, it stops your engine from overheating and possibly being destroyed. That’s bad, FYI. But the good news is that draining your existing coolant and replacing it with new fluid is probably one of the easiest DIY maintenance jobs you can do on your bike. However, always consult your service manual as some bikes require a unique approach.

How Often Should You Replace Motorcycle Coolant?

The answer to this question depends both on where you live and how much riding you do. Most manufacturers will recommend you replace your engine coolant once every two to three years or 15,000 miles, so if you cover a lot of distance you’ll need to do it more regularly.

For those that live in locations with extreme temperature ranges (especially extreme cold) you may need to change your coolant twice a year. In winter, you’ll need a coolant with good anti-freeze specifications to ensure that your cooling system isn’t filled with a block of ice when you go to start it in the morning. In summer if it gets very hot, you may need to replace that with something like WaterWetter that has a reduced boiling point and mix it with distilled water.

Another reason you may need to replace your coolant more regularly is if you go racing. Many motorcycle racing organisations restrict or ban the use of glycol based coolants as they’re slippery and can cause a hazard to other riders should a spill occur. Therefore you’d have to replace such coolant with distilled water.

How Do You Flush and Replace Motorcycle Coolant?

We’ve created a video for you to watch which demonstrates this job but we’ll also describe the process step-by-step below.

Tools you’ll need are a wrench to remove the bolts from your bike, replacement coolant (obviously), distilled water and a container to capture the drained fluids.

1. If required, remove your fairings and the reserve tank so you can access the radiator cap.

2. Locate the drain bolt. To find the drain bolt, follow the pipe from the radiator to the impeller cover. If you’re struggling to find it refer to your owner’s manual.

3. With your wrench, unscrew the drain bolt and make sure you place the container underneath it to capture the drips.

4. Unscrew the radiator cap. Generally you’ll need to unscrew it anti-clockwise half a turn, then push down on it and unscrew it the rest of the way. This release of pressure will allow the coolant to drain from your bike – you’ll need to move your container to capture the coolant.

5. Screw the drain bolt back in with your hands. Don’t tighten it up properly just yet.

6. Pour distilled or demineralized water into the radiator until it fills up. Before unscrewing the drain bolt, turn your bike’s engine on for a few minutes to assist the distilled water to circulate through the system.

7. Unscrew the drain bolt and capture the distilled water in the container.

8. Make sure you also empty the coolant in your reserve tank.

9. Put the drain bolt back in and tighten it according to the torque values as stated in your service manual.

10. Poor your new coolant into the radiator, but do it slowly. By doing it slowly you reduce the amount of air introduced into the cooling system. Fill the reserve tank too.

11. Replace the caps on both the reserve tank and the radiator and run the bike for a period of time until the radiator fan turns on. This will help any air trapped in the system to rise into the reserve tank.

12. Let the bike cool. The expelled air will mean coolant is drawn from the reserve tank into the cooling system, so top up the reserve tank.

13. Make sure you dispose of your old coolant properly. Don’t put it down the drain as it contains numerous chemicals. A local recycling or refuse station will be able to dispose of it correctly.

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