How to Change the Coolant in a 2008 Suzuki DR-Z400S

Shop parts for a 2008 Suzuki DR-Z400S Dirt Bike.

Changing the coolant in your 2008 Suzuki DR-Z400S is essential for peak engine performance and long-term reliability. This versatile dual sport uses a liquid cooling system that, if not maintained, can allow mineral buildup, poor heat transfer, or even engine damage. The following guide is designed specifically for the DR-Z400S, featuring model-specific insights and steps for a hassle-free process.

What Makes the DR-Z400S Cooling System Unique?

  • The 2008 DR-Z400S uses a simple, robust liquid cooling system without a thermostat or water neck bleeder screw if the water neck points straight up–always check your engine's configuration before beginning.
  • Factory coolant is a pre-diluted, ethylene glycol-based mix–always use motorcycle-approved coolant for aluminum components.
  • Overfilling or failing to remove air pockets can result in overheating due to trapped air, so the bleeding process is critical.

What You Will Need

  • Pre-diluted coolant (50/50 ethylene glycol, motorcycle safe)
  • 12mm & 10mm socket/wrench
  • Medium Phillips screwdriver
  • Drain pan
  • Rags or shop towels
  • Optional: compressed air (if flushing system)

Step-by-Step Coolant Change Guide

  1. Prep the Bike
    Ensure the engine is completely cool before you begin. Park the DR-Z400S on a level surface and set the bike upright, using a stand for stability.
    Remove both side covers as needed for easier access to the radiator, water pump, and coolant fill neck.
  2. Remove the Radiator Cap
    Remove the small securing screw if present, then carefully remove the radiator cap to relieve system pressure.
  3. Drain the Old Coolant
    Place your drain pan under the water pump (right side). Remove the 10mm drain bolt from the lower pump cover. Allow all coolant to flow out. Open the radiator cap to speed drainage.
    Tip: Inspect the old fluid—milky, rusty, or sludgy coolant indicates further cleaning or inspection is needed.
  4. Flush (Optional)
    If switching coolant types or the old coolant is heavily contaminated, flush with distilled water. Remove coolant hoses (top and bottom), then gently blow compressed air through to force out any remaining fluid. Reinstall hoses and bolts before proceeding.
  5. Bleed Air (If applicable)
    If your DR-Z400S water neck has a bleed screw, use an 8mm or suitable tool to open it a few turns (do not remove). Some 2008 bikes may not have this feature.
  6. Refill
    Slowly pour new coolant into the right side (radiator fill). If you have a bleed screw, keep it open until coolant starts to flow out, then tighten. Continue filling until the radiator is topped off.
    Also check and top off the overflow reservoir (usually about 1 inch up from the bottom).
  7. Bleed System & Top Off
    To remove any trapped air, gently rock the bike side-to-side a few times. Add more coolant if the level drops.
    Replace the radiator cap securely.
  8. Run the Engine
    With the radiator cap in place, start the bike and allow it to idle until it reaches normal operating temperature. Shut down and let cool.
  9. Final Check & Top Off
    Once cool, remove the radiator cap and check the level again–add coolant as needed. Replace and secure all removed covers and hardware.

Additional Tips for the DR-Z400S Owner

  • Check your coolant and inspect hoses at least once per season (or every 6,000 miles).
  • If your bike has overheated or you've noticed coolant loss, inspect the radiator for damage or leaks before refilling.
  • Always dispose of old coolant responsibly–it is toxic to pets and wildlife.
  • The DR-Z400S has no low-coolant sensor. Regular manual checks are essential. Trapped air is a common cause of overheating after service.

Your 2008 Suzuki DR-Z400S is a reliable workhorse if you keep its cooling system maintained and air-free. With these model-specific steps from MotoSport, you can ride with confidence and keep your engine cool, mile after mile.

Related Shopping Categories

Shop Radiators for a 2008 Suzuki DR-Z400S Dirt Bike.

Shop Coolant for a 2008 Suzuki DR-Z400S Dirt Bike.

Shop Temperature Sensors for a 2008 Suzuki DR-Z400S Dirt Bike.

Shop Tools for a 2008 Suzuki DR-Z400S Dirt Bike.

Shop Radiator Hoses for a 2008 Suzuki DR-Z400S 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.