How to Change the Coolant in a 2018 KTM 300XC
Shop parts for a 2018 KTM 300XC Dirt Bike.
Changing the coolant on your 2018 KTM 300XC is essential routine maintenance, ensuring optimal engine performance & longevity. While KTM’s two-stroke design in this model offers robust off-road power, keeping the cooling system fresh and clean prevents overheating during demanding rides – especially for owners who push the bike in extreme conditions.
What You’ll Need
- New coolant recommended for KTM engines (silicate-free, designed for aluminum engines, premixed or distilled water to mix)
- Catching pan for old coolant
- 8mm or 10mm socket or spanner (check your water pump bolts)
- Funnel
- Rags or shop towels
- Safety gloves & eye protection
Important Notes for the 2018 KTM 300XC
- This model often uses a specific water pump bolt for draining – avoid confusion with adjacent screws. Always verify which bolt is the drain if you reference the manual, as some, especially on late model 300XCs, are not correct in the printed instructions. Owners note the left-side water pump bolt is the correct one on this year’s bike.
- The cooling system holds just over 1L of coolant, so have at least this much ready.
- Let the engine cool completely before starting. Hot coolant can cause burns.
Step-by-Step Coolant Change
- Remove the radiator cap (located under the front shroud) to allow the system to vent and drain smoothly.
- Place a pan underneath the engine, directly below the water pump cover on the right side of the bike.
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Identify & remove the proper water pump drain bolt. On the 2018 KTM 300XC, this is likely the lower left-side bolt on the water pump cover. Loosen the bolt and allow coolant to drain completely. If desired, you can also loosen (but not remove) the other water pump cover bolts to expedite draining.
Tip: Tilting the bike slightly to the left helps expel more old coolant. - Flush (optional but recommended): After draining, refit the bolt, pour in distilled water, and run the engine for a few minutes. Allow to cool, then drain again to remove any residue or old contaminants. Repeat until water runs clear.
- Reinstall & tighten the drain bolt. Torque to factory spec (typically around 6 Nm – check your manual for your bike’s spec).
- Add new coolant. Using a funnel, fill the radiator with fresh coolant up to the bottom of the radiator neck. Squeeze the radiator hoses gently to remove air pockets.
- Bleed air from the system. Some KTM 300XC models may develop airlocks in the system. Elevate the front wheel (raising the front of the bike by 18 to 20 inches), and continue filling until you see liquid at the bleed screw or overflow reservoir, if present, then close everything securely (factory recommends this technique for complete air purge).
- Reinstall the radiator cap securely and wipe away any spills.
- Start the engine & check your work: Let the bike idle until warm. After it cools, check coolant level again. Top off if needed.
- Dispose of used coolant responsibly. Don’t pour it down drains or in the garage—take it to a recycling center.
Special Considerations for the 300XC
- Keep a close eye on the radiator and hose integrity. High-vibration, two-stroke engines like this can develop leaks or loose fittings over time, especially after hard riding or crashes.
- Check and replace the radiator cap if you detect pressure loss or see coolant venting prematurely.
- For aggressive woods riding, consider a coolant formulated for extreme heat (or a high-performance additive). Monitor for signs of overheating—steam, boil-over, or frequent coolant loss.
Keeping your KTM 300XC’s cooling system in top shape ensures reliability and performance whether you’re tackling technical trails, open deserts, or races.
Related Shopping Categories
Shop Radiators for a 2018 KTM 300XC Dirt Bike.
Shop Coolant for a 2018 KTM 300XC Dirt Bike.
Shop Temperature Sensors for a 2018 KTM 300XC Dirt Bike.
Shop Tools for a 2018 KTM 300XC Dirt Bike.
Shop Radiator Hoses for a 2018 KTM 300XC 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.