How to Change the Coolant in a 2018 Yamaha YZ450FX
Shop parts for a 2018 Yamaha YZ450FX Dirt Bike.
Maintaining proper engine temperature is key to maximizing performance and extending engine life on your 2018 Yamaha YZ450FX. One often overlooked element is the regular replacement of your engine coolant, which prevents overheating and corrosion, especially in high-stress riding environments. Here is MotoSport’s robust, rider-focused guide to changing your coolant with special insights for the YZ450FX platform.
What You'll Need
- Fresh coolant (high-performance motorcycle coolant recommended for aluminum engines)
- Basic hand tools (8mm wrench or socket, screwdrivers)
- Shop towels
- Catch pan for old coolant
- Gloves and safety glasses
Step-by-Step Instructions
- Let the engine cool completely before starting. Hot coolant can cause burns. Work in a well-ventilated space.
- Remove any bodywork or guards as necessary to access the radiators and drain bolt.
- On some YZ450FX models, radiator louvers or skid plates may partially obstruct access.
- Place your catch pan under the right side of the engine (water pump area).
- Remove the radiator cap.
- Slowly loosen to release any pressure, then fully remove the cap to allow the coolant to drain efficiently.
- Locate and remove the coolant drain bolt.
- The coolant drain bolt is typically found on the lower water pump cover, near the right side engine case. Use an 8mm wrench or socket to remove it.
- Allow all coolant to fully drain.
- Tipping the bike slightly or gently rocking it can help evacuate any trapped coolant. Inspect the coolant for debris or discoloration as an indicator of possible future issues.
- Reinstall the drain bolt.
- Replace the washer if damaged. Torque the bolt to manufacturer specification to prevent leaks.
- Refill the radiator with fresh coolant.
- Use a funnel for accuracy and avoid overfilling. Fill slowly until the coolant reaches just under the radiator neck.
- Bleed the system.
- Gently rock the bike side-to-side and squeeze the coolant hoses to dislodge any trapped air. Top off the coolant as needed.
- Reinstall the radiator cap securely.
- Start the engine.
- Let the engine idle briefly, then shut it off and recheck coolant level. Add more coolant if necessary.
- Reinstall any removed bodywork or guards.
YZ450FX-Specific Notes
- The 2018 YZ450FX shares most of its cooling system hardware with the YZ450F but features an off-road-tuned powerplant and a larger fuel tank. Overheating is a risk in technical or slow terrain, making fresh coolant especially important for trail riding.
- If you regularly ride in extreme temperatures or race scenarios, consider high-performance or race-specific coolants and check your radiator for bent fins or built-up debris.
- Inspect the water pump housing and drain bolt area for signs of leaks—these models can develop minor seepage with age.
Maintenance Tips
- Replace coolant every 1–2 years, or more frequently in harsh conditions.
- Only use coolants compatible with aluminum radiators and magnesium engine cases.
- Never mix different coolant types—flush the system fully if switching brands or types.
Performing this essential maintenance makes a big difference in long-term bike performance. Stay ahead of the curve and keep your 2018 YZ450FX running cool on every ride.
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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.