How to Change the Coolant in Your 2018 KTM 150SX
Shop parts for a 2018 KTM 150SX Dirt Bike.
Keeping the cooling system in top condition ensures your 2018 KTM 150SX delivers maximum performance on the track or trail. Neglecting coolant replacement can lead to overheating, reduced efficiency, and expensive repairs. Below, MotoSport guides you through the process of changing the coolant on your 150SX, with important notes specific to your MMY dirt bike.
What You Need
- New coolant (compatible with KTM two-stroke engines)
- 8mm socket or wrench
- Container to catch old coolant
- Funnel
- Shop towels
- Torque wrench (recommended for accuracy)
- Protective gloves & eyewear
Important Safety Precautions
- Always let your engine & cooling system fully cool before starting. Opening a hot radiator cap can cause severe burns from pressurized coolant release.
If coolant contacts your skin, wash with soapy water.
If coolant contacts your eyes, flush immediately with water and seek medical attention.
Step-by-Step Coolant Change for 2018 KTM 150SX
- Access the Radiator
Remove your seat and side shrouds if necessary, for clear access to the radiator cap. - Open the Radiator Cap
With the engine fully cool, slowly open the radiator cap to relieve any residual pressure. - Drain the Old Coolant
Position your container below the water pump drain bolt, located at the bottom right side of the engine case.
Use the 8mm socket to remove the drain bolt. Allow all coolant to drain completely. Inspect the old coolant; milky or rusty discoloration indicates possible engine issues. - Flush the System (Optional, Recommended)
If your coolant shows signs of heavy contamination, flush with distilled water. Reinstall the drain bolt, fill with distilled water, run the engine briefly, let it cool, and drain again. - Reinstall and Torque the Drain Bolt
Clean the bolt and sealing surfaces. Reinstall the drain bolt and torque it to the manufacturer's spec (refer to your owner's manual for exact value). - Fill the Cooling System
Using your funnel, carefully fill the radiator with fresh coolant. Slowly pour to prevent air pockets.
For the 2018 KTM 150SX, fill up to the base of the filler neck but do not overfill. - Bleed Air from the System
To ensure no air is trapped, gently rock the bike from side to side or squeeze radiator hoses. Some KTM two-strokes have a small bleeder screw on the cylinder head or thermostat housingconsult your service manual and open briefly if equipped. - Check Coolant Level and Replace Radiator Cap
Re-check the coolant level, top off as needed, and securely reinstall the cap. - Wipe Down & Dispose of Waste
Clean any spilled coolant from your bike. Dispose of old coolant responsibly according to local environmental guidelines.
What Owners Should Know about the 2018 KTM 150SX Cooling System
- The 2018 150SX uses a high-capacity radiator system with a race-tuned 2-stroke engine that generates significant heat during prolonged or aggressive ridingstay proactive with coolant maintenance.
- If you ride in sandy or muddy environments, check and clean the radiator fins regularly to ensure optimal airflow and cooling.
- Only use coolants compatible with aluminum engine components and KTM specifications to prevent corrosion or internal damage.
- If performing repeated coolant changes due to overheating, inspect your water pump seals and impeller for wear.
Final Thoughts
Changing the coolant on your 2018 KTM 150SX is routine but vital. Stay on top of service intervals, use the right products, and check your cooling system after extreme rides. Regular maintenance keeps your KTM performing strong – and MotoSport has all the parts and fluids you need to get the job done right.
Related Shopping Categories
Shop Radiators for a 2018 KTM 150SX Dirt Bike.
Shop Coolant for a 2018 KTM 150SX Dirt Bike.
Shop Temperature Sensors for a 2018 KTM 150SX Dirt Bike.
Shop Tools for a 2018 KTM 150SX Dirt Bike.
Shop Radiator Hoses for a 2018 KTM 150SX 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.