How to Flush a Motorcycle Radiator

Written by matt haupt | 13/05/2017
How to Flush a Motorcycle Radiator
Keep your motorcycle running smoothly---and longer---by performing periodic radiator flushes. (motorcycle image by Goran Bogicevic from

Flushing your motorcycle's radiator is an easy and highly recommended way of keeping your motorcycle well maintained throughout its life. Failing to flush the radiator on a regular basis may cause some of your engine parts to overheat or freeze, necessitating expensive repairs. Performing scheduled maintenance on the motorcycle can save you thousands of dollars on repairs from wear and tear alone.

Loosen the drain bolts and air bleeder bolt attached to the radiator. Remove any other engine parts blocking access to the radiator, such as the gas tank. The make and model of the motorcycle will determine the number of drain bolts and the tool required for their removal---usually a wrench.

Place the drain pan beneath the radiator's drain bolts you have just loosened.

Remove the radiator cap.

Remove all drain bolts and the air bleed bolt with your wrench. Coolant will begin to pour out near the water pump. Keep the drain pan in place until you have emptied all coolant from the radiator.

Insert all bolts back into their proper locations.

Fill the radiator with water.

Loosen all bolts again to drain the water from the radiator. Repeat filling and flushing the water from the radiator until the water drains clear.

Disconnect the hose connecting the radiator to the overflow bottle.

Rinse the overflow bottle and continue until you have removed all residue from the inside-bottom of the container. Allow the bottle to dry completely.

Remove the air bleed bolt, and drain all excess air from the system.

Turn on the motorcycle engine to remove any trapped air inside the system, which should only take a few seconds.

Replace all bolts, the radiator cap and the overflow bottle. Connect the hose. Double-check to ensure that you have secured all of these components.

Fill the radiator's overflow bottle with a mixture of motorcycle-safe coolant and distilled water until it reaches the full line. (Follow the directions on the coolant bottle for the proper ratio of coolant to water.)

Things you need

  • Wrenches
  • Drain pan
  • Motorcycle-safe coolant

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