How to Change the Coolant in a 2018 Husqvarna FX350

Shop parts for a 2018 Husqvarna FX350 Dirt Bike.

Maintaining the proper cooling system is critical for the performance and longevity of your 2018 Husqvarna FX350. Coolant should be changed at recommended intervals or whenever you notice overheating, contamination, or after heavy use in extreme conditions. The process is straightforward but does require careful handling due to the toxicity of most coolants. Here is MotoSport's proprietary step-by-step guide for changing the coolant in your FX350.

Important: Read Before You Begin

  • Ensure the engine is completely cool before starting. Opening the radiator cap on a hot engine can result in serious burns or injury.
  • Use a good-quality motorcycle coolant. Avoid automotive coolants which may not be compatible with your dirt bike's materials.
  • Work in a well-ventilated area and always keep coolant out of reach of children & pets. Wear gloves and eye protection.
  • The 2018 FX350 uses a liquid-cooled engine nearly identical to the FC/FE series, so techniques apply universally across these models.

Tools & Supplies You'll Need

  • Fresh coolant (check your owner's manual or choose a high-performance motorcycle coolant)
  • Screwdriver or socket set (to remove the drain bolt and radiator cap)
  • Drain pan or suitable container
  • Funnel for refilling
  • Clean water (distilled preferred) for flushing
  • Torque wrench (recommended for precise reassembly)
  • Gloves and safety glasses

Step-by-Step Coolant Change Instructions

  1. Position the Motorcycle
    Place the FX350 upright on a stand. Ensure it is stable and will not tip during service.
  2. Remove Radiator Cap to Release Pressure
    Locate the radiator cap on the left upper side of the radiator. Slowly remove the cap to release any built-up pressure.
  3. Drain the Old Coolant
    Place your drain pan beneath the water pump cover (right side of the engine case).
    Remove the coolant drain screw from the cover using your socket or screwdriver. Allow all coolant to drain completely until the flow tapers off. Be sure to dispose of coolant safely – it is hazardous to people and the environment.
    For best results, you can lightly rock the bike side-to-side to ensure all coolant is removed.
    After draining, reinstall and torque the drain screw (M6, 10 Nm or 7.4 lbf–ft) with a new seal ring if necessary.
  4. Flush the System (Recommended)
    Fill the radiator with clean distilled water. Reinstall the cap and briefly run the engine (under a minute) to circulate. Shut off and repeat the draining process to remove remaining contaminants.
    Repeat if the drained water is still discolored.
  5. Refill with New Coolant
    With the engine off and radiator drain screw reinstalled, use a funnel to slowly fill the radiator up to the lower edge of the filler neck.
    Gently tip the bike from side to side to help air bubbles escape. Fill as needed until the level is steady.
  6. Bleed the Cooling System
    With the bike upright, start the engine and let it idle for a minute with the radiator cap off (monitor level – add coolant if needed). Shut the bike off and replace the radiator cap.
  7. Final Checks
    Inspect for leaks at the drain screw, caps, and hoses.
    After the first ride, double-check the coolant level and top off as required.

2018 Husqvarna FX350—Things to Know

  • The FX350 features a compact, high-revving DOHC engine with tight coolant passageways—regular maintenance prevents overheating and extends engine life.
  • The radiator is integrated closely to the frame for maximum airflow. Keep fins clean and straight to ensure cooling efficiency.
  • Consider adding an auxiliary coolant reservoir or overflow tank, especially for rugged racing conditions. It offers extra protection against overheating and coolant loss.
  • Always monitor cooling fan performance (if fitted), as electrical or sensor faults can limit coolant circulation and lead to overheating.

Coolant Safety Reminders

  • Coolant is toxic—avoid contact with skin, eyes, and clothing. In case of exposure, rinse thoroughly and seek medical attention as necessary.
  • Dispose of old coolant at a certified recycling facility. Never pour it down the drain or onto the ground.

With regular coolant changes, your 2018 Husqvarna FX350 will run cooler, last longer, and be ready for anything the trail throws your 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.