How to Change the Coolant in a 2018 Yamaha YZ250FX
Shop parts for a 2018 Yamaha YZ250FX Dirt Bike.
Maintaining proper coolant levels and refreshing the coolant in your 2018 Yamaha YZ250FX is essential for protecting the engine from overheating and corrosion. The steps below detail a robust, MotoSport-approved process to change the coolant, optimized specifically for this MMY dirt bike. Yamaha's YZ250FX comes with an aluminum engine and high-performance radiator–regular coolant service preserves both performance and bike longevity.
What You'll Need
- High-quality ethylene glycol coolant formulated for aluminum engines (50/50 coolant-water mix)
- Clean, soft water (for system flushing if needed)
- Socket wrench set
- Drain pan/container
- Torque wrench (spec: 10 Nm for drain bolt)
- New copper washer for drain bolt (recommended)
- Protective gloves and rags
Step-by-Step Coolant Change Process
- Ensure Safety
- Always start with a completely cold engine. Removing the radiator cap when hot can cause dangerous coolant splashes and pressure release.
- If coolant gets on painted or plastic parts, wash it off immediately to prevent damage.
- Drain Old Coolant
- Set the bike upright securely, then position a drain pan directly under the engine.
- Remove the coolant drain bolt at the base of the water pump. Keep the bolt and copper washer safe–replace the washer if it is damaged or worn.
- Slowly remove the radiator cap (top of the left radiator) to begin draining. Wait for all coolant to exit.
- Flush Cooling System
- For best results, flush the system by pouring clean, soft water into the radiator until it runs clear from the drain. This removes residual old coolant or contaminants.
- Drain the flush water completely.
- Reinstall Drain Bolt
- Attach a new or cleaned copper washer to the drain bolt.
- Install and tighten the drain bolt to 10 Nm (7.2 ft–lb) torque.
- Add New Coolant
- Prepare a 50/50 mix: half ethylene glycol coolant, half soft water. Do not use straight water or non-recommended coolant, as this can damage your aluminum engine.
- Pour coolant into the radiator until it reaches the top and is visible in the filler neck.
- Bleed Air from the System
- With the radiator cap still off, gently tilt the bike side to side to help any air bubbles escape.
- Start the engine briefly and let it idle (while observing coolant level); top off as necessary.
- Install the radiator cap securely.
- Check for Leaks and Final Level
- Inspect the drain bolt and radiator for leaks after a short idle period.
- Once the engine cools, recheck the coolant level and top off if needed.
2018 YZ250FX Model-Specific Notes
- Coolant Capacity: 1.20 L (1.27 US qt)
- This model uses a high-compression aluminum cylinder head; always use a coolant designed for modern aluminum engines to prevent internal corrosion.
- Carefully monitor gasket and hose condition–the YZ250FX's lightweight design relies on properly sealed and maintained hoses for optimal cooling.
- Always dispose of old coolant responsibly, as many coolants are toxic and harmful to pets and the environment.
Routine coolant changes will keep your YZ250FX running at peak performance and help avoid costly engine repairs due to overheating or corrosion. For all OEM and performance parts, shop parts for a 2018 Yamaha YZ250FX 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.