How to Change the Coolant in a 2020 Honda CRF450RX
Shop parts for a 2020 Honda CRF450RX Dirt Bike.
The 2020 Honda CRF450RX is a high-performance off-road machine engineered for racing and aggressive trail riding. Regular coolant changes are essential for maintaining peak engine temperature and reliability under demanding riding conditions. Follow this MotoSport-exclusive guide to properly change the coolant in your CRF450RX, and check out some model-specific notes to keep your bike running at its best.
What You Need
- New coolant (use a high-quality glycol-based coolant formulated for dirt bikes)
- Distilled water (if required to dilute concentrated coolant)
- Drain pan
- 8mm and 10mm sockets or wrenches
- Fresh copper washer for the drain bolt
- Funnel
- Clean rags
- Screwdriver
- Torque wrench
- Protective gloves
Step-by-Step Coolant Change Instructions
- Ensure the engine is completely cool before starting. Never open the radiator cap or drain plug when the engine is hot—risk of serious burns.
- Remove the radiator shrouds and, if in the way, the engine guard by unscrewing their bolts with a 10mm wrench. Set aside the hardware for reinstallation.
Tip: For the CRF450RX, removing the engine guard helps access the water pump area and the radiator cap more easily. - Place a drain pan beneath the water pump area on the right side of the engine.
- Remove the radiator cap to allow air in—this helps the coolant drain faster.
- Locate the water pump drain bolt (bottom bolt on water pump cover) and remove it with an 8mm socket. Let the coolant fully drain into the pan.
Model note: Keep track of the copper washer on the drain bolt, and always replace it when reinstalling to prevent leaks. - Check the condition of the old coolant. Milky or rusty fluid signals internal leaks or corrosion and requires further inspection.
- Reinstall the drain bolt with a new copper washer. Torque to 10 Nm (7 lbfft) for a secure fit–don't over-tighten.
- Slowly pour new coolant into the radiator up to the bottom of the filler neck. Use a funnel to avoid spills.
- If using concentrated coolant, always mix with distilled water as per product instructions. Do not use tap water (to avoid mineral deposits).
- Reinstall the radiator cap securely to prevent leaks and ensure proper radiator pressure.
Failure to install the cap properly can lead to overheating and engine damage. - Start the engine and let it idle for several minutes. Gently rev the engine a few times. Watch for rising coolant level as any air pockets bleed out.
- Shut the engine off, allow it to cool, and re-check the coolant level. Top off if necessary. Double-check for leaks around the drain bolt, hoses, and radiator seams.
- Reinstall the engine guard, radiator shrouds, and any bodywork you removed.
- Inspect the overflow/vent tube for proper routing and ensure the system remains sealed.
2020 CRF450RX Owner's Tips & Reminders
- The CRF450RX shares much of its cooling system design with the CRF450R but is factory-equipped for off-road racing. Intense use and slow-speed technical terrain may cause higher heat buildup, so check coolant condition after heavy rides.
- If you ride in extreme temperatures, consider a coolant formulated for racing or high-temperature operation.
- Inspect radiator hoses and clamps for wear while performing coolant changes. Replace anything that shows signs of aging or damage.
- If you ever remove the coolant temperature sensor (mounted at the left radiator outlet), ensure the crush washer is replaced and torque to 18 ft-lb for proper sealing—this is a common spot for leaks when not properly secured.
- Coolant capacity after draining is approximately 1.03 liters (1.09 US qt). Do not overfill; allow space for thermal expansion.
- Always check the cooling fan switch and wiring (if equipped). Overheating issues often trace back to poor fan operation or blocked radiator fins.
Final Checks
- Double-check all fasteners and clamps.
- Monitor coolant level after the first few heat cycles and top off if needed.
- Dispose of used coolant properly—it is toxic and cannot be poured down drains or onto the ground.
Related Shopping Categories
Shop Radiators for a 2020 Honda CRF450RX Dirt Bike.
Shop Coolant for a 2020 Honda CRF450RX Dirt Bike.
Shop Temperature Sensors for a 2020 Honda CRF450RX Dirt Bike.
Shop Tools for a 2020 Honda CRF450RX Dirt Bike.
Shop Radiator Hoses for a 2020 Honda CRF450RX Dirt Bike.
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.