How to Change the Coolant in a 2006 Suzuki DRZ400S

Shop parts for a 2006 Suzuki DRZ400S Dirt Bike.

Keeping your 2006 Suzuki DRZ400S running at its peak means regular maintenance of critical components, and the cooling system is no exception. Fresh coolant improves engine performance – protecting against corrosion, overheating, and freeze damage. This guide provides step-by-step instructions unique to the DRZ400S, including important model-specific notes every owner should know.

What You Need

  • Pre-mixed 50/50 motorcycle coolant (avoid silicates and tap water)
  • Socket set (10mm, 12mm)
  • Phillips screwdriver
  • Drain pan
  • Clean rag
  • Shop gloves

Preparation

  • Ensure the engine is completely cool before starting work – hot coolant can cause serious burns.
  • Place your DRZ400S on a level surface using the side stand or a work stand.

1. Remove the Side Cover

  • Locate and remove the bolts holding the left side panel (use a 12mm socket).
  • Gently take off the panel to access the radiator and water pump cover area.

2. Remove the Radiator Cap

  • Unscrew and remove the small screw securing the radiator cap on the right radiator.
  • Carefully remove the cap to relieve system pressure (do this only when cool).

3. Drain the Old Coolant

  • Position your drain pan beneath the water pump on the right side of the engine.
  • Locate the coolant drain bolt (10mm) on the water pump cover and carefully remove it.
  • Let the old coolant fully drain – loosen the radiator cap further if needed for better flow.
  • Reinstall the drain bolt once draining is complete; torque to spec.

4. Bleed Air from the System (Model-Specific Steps)

  • The DRZ400S often has two air bleed screws – one on the water neck at the front of the cylinder head, and one on top of the left radiator. Some models may have only one or neither.
  • If your DRZ400S has bleeder screws, open them a few turns – don't remove completely.

5. Refill with Fresh Coolant

  • Slowly pour coolant into the right radiator until it's full. As you fill:
    • Observe air escaping from the open bleed screws.
    • Close each bleeder as soon as coolant flows out – start with the water neck, then the left radiator screw.
  • Continue filling until the radiator remains topped off, occasionally rocking the bike gently from side to side to help release trapped air.

6. Check & Top Off

  • Reinstall the radiator cap securely.
  • Start the engine and let it idle, monitoring the temperature.
  • Shut off the engine and allow it to cool fully. Remove the cap and check the coolant level – top off if necessary.
  • Fill the coolant overflow bottle (located near the left rear subframe) with about 1 inch of coolant.

Model Notes & Tips

  • Not every DRZ400S will have both air bleeder screws. If the water neck points straight up, there may be no bleeder screw or thermostat. In this case, fill the radiator more slowly, letting air escape naturally as you top off and gently rock the bike left and right.
  • The DRZ400S does not typically run a thermostat from the factory, which speeds up coolant flow compared to street bikes – check for leaks after the first warm-up.
  • Never mix coolant types unless compatible. Always use motorcycle-specific coolant, as automotive formulas may contain silicates that damage water pump seals.

Final Checks

  • Inspect the coolant level in both the radiator and overflow after your first ride.
  • Check for any visible leaks and ensure hoses/clamps are secure.
  • Service the system every two years, or more often if riding in extreme conditions.

Performing this service as part of routine maintenance will help your Suzuki DRZ400S deliver reliable performance for every adventure, on or off the trail.

Related Shopping Categories

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Shop Radiator Hoses for a 2006 Suzuki DRZ400S 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.