How to Change the Coolant in a 2018 KTM 350EXCF

Shop parts for a 2018 KTM 350EXCF Dirt Bike.

Routine coolant changes are crucial to keep your 2018 KTM 350EXCF running cool on the toughest trails. This step-by-step guide from MotoSport walks you through the process with tips and model-specific notes to ensure you get the job done right.

Tools & Supplies Needed

  • 8mm socket or wrench
  • Phillips or flat-head screwdriver (if radiator shrouds need removal)
  • Drain pan or container
  • Funnel
  • Fresh coolant (use KTM-approved or high-quality equivalent)
  • Distilled water (optional, for flushing)
  • Gloves and eye protection

Preparation

  • Ensure the engine is completely cool before starting–hot coolant can cause severe burns.
  • Place the bike securely on a stand or level surface.

Step 1: Remove the Radiator Cap

  • Use a rag to gently open the radiator cap on the left side of the bike. This relieves any system pressure and allows coolant to drain smoothly.

Step 2: Locate and Remove the Drain Bolt

  • The coolant drain bolt is located on the water pump cover, typically visible on the right-hand side, just below the engine cases.
  • Use an 8mm socket or wrench to remove the bolt. Place your drain pan underneath first to catch the old coolant.

Step 3: Drain the Coolant

  • Allow all coolant to drain from the system.
  • If you want to perform a flush, replace the drain bolt, fill with distilled water, and briefly run the engine (remember–engine should not get hot). Drain again.

Step 4: Reinstall the Drain Bolt

  • Ensure the drain bolt and its washer are clean and undamaged. Reinstall and tighten securely.

Step 5: Refill with Coolant

  • Using a funnel, pour the recommended coolant slowly into the radiator until full.
  • On the 350EXCF, ensure the front wheel is on level ground, so air pockets do not form in the cooling system.
  • Gently rock the bike from side to side to help dislodge trapped air.

Step 6: Bleed the System

  • Slowly add coolant until the level stops dropping. Some models may have cylinder-head bleed screws–if equipped, briefly remove to vent air until a steady stream of coolant emerges, then retighten.
  • Reinstall the radiator cap securely.

Step 7: Start and Check

  • Start the engine and let it idle for a few minutes, monitoring coolant level. Shut off, allow to cool, and recheck level. Top off as necessary.
  • Inspect for leaks at the drain bolt, hoses, and radiator cap.

Model-Specific Tips for the 2018 KTM 350EXCF

  • The 350EXCF uses a pressurized cooling system designed for off-road endurance. Sticking to the specified coolant type and correct mixture is critical for optimal performance and engine wear protection.
  • Look out for air pockets during refilling–this model is prone to trapping air if not bled carefully, potentially causing overheating.
  • Wear eye protection when working with coolant, and clean any spills promptly off painted or plastic parts.

Coolant Disposal

  • Coolant is hazardous to people, animals, and the environment. Transport used coolant to a proper recycling center or hazardous waste facility.

When to Change Coolant

  • KTM recommends changing coolant every 2 years or as indicated by poor cooling, dirty coolant, or after deep water crossings.

Regular coolant changes help your 2018 KTM 350EXCF deliver championship-level performance and reliability on every ride. Trust MotoSport for parts, tools, and expert support as you maintain your bike the right way.

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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.