How to Change the Coolant in a 2018 Honda CRF150R

Shop parts for a 2018 Honda CRF150R Dirt Bike.

Staying on top of coolant changes is key to protecting the high-revving engine in your 2018 Honda CRF150R. Whether you race or ride trails, proper cooling is vital for consistent power output and a long service life. This proprietary MotoSport guide walks you through the process step by step, including specific notes for your CRF150R.

What You'll Need

  • Fresh coolant compatible with aluminum radiators
  • Drain pan
  • 8mm socket or wrench
  • Copper washer (optional but recommended)
  • Distilled water for flushing (optional)
  • Funnel
  • Rags for cleanup
  • Protective gloves

Preparation

  • Make sure your CRF150R engine is cool to prevent burns and pressure buildup.
  • Stand the bike upright on a stable stand for proper draining.
  • Remove any shrouds or panels blocking access to the radiator cap as needed.

Draining the Old Coolant

  • Place a drain pan directly beneath the water pump area (right side of engine).
  • Use the 8mm socket to remove the drain bolt at the bottom of the water pump. This bolt should have a copper washer.
  • Slow initial flow is normal–to ensure proper draining, remove the radiator cap to allow air in and help the coolant flow out rapidly .

Flushing (Optional but Recommended)

  • To remove residue and prolong the life of the new coolant, pour distilled water into the radiator and let it drain out completely with the drain bolt still removed.
  • Repeat until the water runs clear .

Reinstalling the Drain Bolt

  • Replace the copper washer to ensure a proper seal. Reinstall the drain bolt and tighten securely–do not overtighten to avoid stripping the threads.

Adding Fresh Coolant

  • With the drain bolt in place, pour the new coolant through the radiator neck. 
  • Use a funnel to avoid spills and fill until the coolant is just below the bottom of the radiator neck.
  • Lightly shake the bike side to side to burp trapped air. 
  • If possible, slowly kick the engine (without starting) a few times to help any remaining air escape .

Final Steps

  • Reinstall the radiator cap securely–it should click twice so you know it is fully seated .
  • Wipe up any spilled coolant and reinstall any removed bodywork.
  • Start the engine and let it idle with the cap on for several minutes. Shut it off, let it cool, and re-check the coolant level, topping up as needed–the level may drop slightly as air works out .

CRF150R-Specific Notes

  • The 2018 CRF150R uses a high-revving, liquid-cooled engine with a nickel-silicon-carbide cylinder for optimal heat transfer, so fresh, quality coolant is absolutely crucial.
  • Always use a coolant compatible with aluminum components to stave off corrosion in the radiator and engine.
  • This model is designed without an overflow catch bottle–any excess coolant will escape via the overflow tube if overfilled .
  • Flushing is especially important after any engine work or if signs of overheating or contamination are present.

Disposal and Environmental Tips

  • Never dump used coolant. Take it to an approved recycling or hazardous waste facility.

Looking to stock up or refresh more than just your coolant system? Shop parts for a 2018 Honda CRF150R Dirt Bike.

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Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.