How to Change the Coolant in a 2019 Yamaha YZ450FX: A Step-by-Step Guide
Shop parts for a 2019 Yamaha YZ450FX Dirt Bike.
Changing the coolant in your 2019 Yamaha YZ450FX is essential maintenance for reliable performance, especially for hard Enduro and GNCC-style riding that the FX is designed for. With a compact aluminum frame and a high-performance engine, proper cooling is critical to avoiding overheating on technical trails.
What You Will Need
- Fresh, compatible coolant (avoid using plain water)
- 10 mm socket or wrench
- Phillips screwdriver (for any shrouds or guards, if necessary)
- Clean rag or paper towels
- Drain pan or container
- Optional: compressed air (for full flush)
Step-By-Step Instructions
- Start With a Cool Engine: Let your bike cool down completely before performing any work on the cooling system. Hot coolant can spray under pressure and cause burns.
- Remove the Radiator Cap: Carefully unscrew the radiator cap, which is located on the left side of your YZ450FX near the air filter. Removing the cap helps the old coolant drain cleanly by allowing air to flow into the system.
- Locate & Remove the Drain Bolt: Place your drain pan underneath the water pump area on the right side of the engine. Use your 10 mm socket to remove the coolant drain bolt (usually found on the lower part of the water pump cover). Allow all coolant to drain completely.
- Optional: Flush the System: For a thorough job or if switching coolant types (such as to a non-glycol-based race coolant), you can detach the lower radiator hose and blow compressed air through the system to clear residual fluid. Always reattach and securely fasten any removed hoses.
- Inspect & Replace the Bolt: Inspect the drain bolt and washer for wear or damage—replace if needed for a tight seal. Tighten the drain bolt securely.
- Refill With New Coolant: Slowly pour fresh coolant into the top of the radiator until it reaches just below the neck. The YZ450FX has a compact radiator system, so use a funnel to prevent spills and overfilling.
- Bleed the Cooling System: Slowly rock the bike side to side to release trapped air. Squeeze the radiator hoses gently to help the coolant circulate and dislodge any air bubbles, then top off as needed.
- Reinstall the Radiator Cap: Once the level is correct and air fully bled, replace the radiator cap securely.
- Start & Warm Up: Start the engine and let it reach operating temperature while watching for leaks and monitoring the coolant level. Shut off the bike, allow it to cool, and recheck the coolant level—top off if necessary.
Notes for YZ450FX Owners
- The 2019 YZ450FX uses a close-ratio transmission, and the engine runs hotter than motocross models during slow-speed technical riding—fresh coolant helps prevent boil-over in tough conditions.
- Yamaha recommends checking coolant every 6 months or 20 hours of operation, whichever comes first. For prolonged high-RPM racing or extreme terrain, inspect more frequently.
- Always use coolant safe for aluminum engines; avoid mixing types unless specified as compatible.
Regularly changing your coolant is an easy but critical task for keeping your Yamaha YZ450FX performing at its peak, whether you're racing or hitting the trails.
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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.