How to Change the Coolant in a 2018 KTM 300XCW

Shop parts for a 2018 KTM 300XCW Dirt Bike.

Keeping your 2018 KTM 300XCW performing at its peak means routine maintenance–and changing the coolant is essential for protecting your high performance two-stroke from overheating and corrosion. The steps below offer a proprietary MotoSport guide tailored specifically for KTM's renowned 300XCW, highlighting tips and attention areas unique to this dirt bike model.

What You'll Need

  • Fresh coolant compatible with 2018 KTM 300XCW
  • Distilled water (for flushing, if desired)
  • Drain pan
  • Socket driver and appropriate sockets
  • Shop towels or rags
  • Funnel
  • Protective gloves

Step 1: Preparation

  • Allow the bike to cool completely before starting. Never open the radiator cap on a hot engine.
  • Position the bike upright on a stand for stability and easy access.
  • Remove any plastics or guards as needed to access the radiator cap and water pump area.

Step 2: Drain the Old Coolant

  • Locate the coolant drain bolt on the water pump cover–on the right side of the engine. Place a drain pan beneath to catch the old fluid.
  • Remove the radiator cap first to allow air in and help the coolant drain faster.
    If the flow is slow, gently tilt the bike to the opposite side to help evacuate the last of the coolant from each radiator, as the 300XCW uses two radiators connected at the top and bottom which drain simultaneously.
  • Remove the drain bolt to let coolant flow out completely. Dispose of the old coolant responsibly–never down the drain or into the environment.

Step 3: (Optional) Flush the System

  • If your coolant was especially dirty, pour distilled water into the radiator, replace the cap and start the engine briefly for a few seconds, then repeat the drain process. This helps eliminate lingering contaminants or old coolant residues.

Step 4: Inspect and Reinstall

  • Check the condition of the drain bolt washer and replace if damaged to prevent leaks.
  • Reinstall and torque the drain bolt according to KTM specifications for the 2018 300XCW (usually snug plus a quarter turn).

Step 5: Refill with New Coolant

  • Slowly fill the radiator with new coolant until it reaches the base of the filler neck. On this model, you may need to "burp" the radiators by gently squeezing the hoses to release any trapped air.
  • The 2018 300XCW features a cylinder head bleed screw for air evacuation. Loosen it slightly as you fill, allowing any air to escape, then tighten it once pure coolant emerges.
  • Reinstall the radiator cap securely.

Step 6: Final Check

  • Start the engine and let it idle with the radiator cap in place. Once the thermostat opens, the coolant will circulate, and any trapped air should move to the top. Shut off the bike and let it cool, then check and top off the coolant level if needed.
  • Check for leaks at the drain bolt, hoses, and around the radiators. Reinstall plastics and guards as needed.

Model-Specific Tips for the 2018 KTM 300XCW

  • The dual-radiator setup means draining may take a bit longer–ensure both are empty before refilling for a complete change.
  • If your KTM overheats frequently, check for clogs in the radiators or consider a higher efficiency aftermarket radiator cap or fan kit.
  • KTM recommends checking the coolant level often, especially after hard rides since two-stroke models like the 300XCW can run hotter during extended technical riding.
  • Always use a coolant compatible with aluminum engine parts and O-rings commonly found on KTMs. Avoid mixing coolants of different colors or chemistries.

Regular coolant changes not only keep temperatures in check but help safeguard the 2018 KTM 300XCW's legendary engine for seasons to come. If you need KTM-specific parts or accessories, MotoSport has you covered.

Related Shopping Categories

Shop Radiators for a 2018 KTM 300XCW Dirt Bike.

Shop Coolant for a 2018 KTM 300XCW Dirt Bike.

Shop Temperature Sensors for a 2018 KTM 300XCW Dirt Bike.

Shop Tools for a 2018 KTM 300XCW Dirt Bike.

Shop Radiator Hoses for a 2018 KTM 300XCW 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.