How to Change the Coolant in a 2010 Suzuki DR-Z400S

Shop parts for a 2010 Suzuki DR-Z400S Dirt Bike.

Changing the coolant on your 2010 Suzuki DR-Z400S is a straightforward maintenance task that is key for maximum engine performance and longevity. The DR-Z400S, with its liquid-cooled, single-cylinder engine, relies on proper coolant flow & air-free circulation–especially during long rides or tight trails where airflow through the radiators is sometimes limited. Here is a step-by-step DR-Z400S coolant change guide, including model-specific notes.

What You Need

  • Socket/ratchet set (10mm & 12mm sizes suggested)
  • Phillips screwdriver
  • Drain pan
  • Fresh coolant (50/50 pre-mix recommended)
  • Optional: shop towels, funnel, safety gloves

Step-by-Step Guide

  1. Cool the Engine: Ensure the engine is completely cool before beginning. Hot coolant can cause serious burns.
  2. Remove the Side Cover: Using a 12mm socket, take off the plastic left lower side panel. This provides access to the water pump housing and coolant drain bolt.
  3. Remove the Radiator Cap: Loosen the small screw that secures the radiator cap, then carefully remove the cap itself to relieve system pressure and allow for full drainage.
  4. Drain the Coolant: Place a drain pan under the water pump cover. Use a 10mm socket to remove the drain bolt at the bottom of the water pump. Let the coolant fully drain from the system.
  5. Air Bleed Screws: Locate the air bleed screw on the top front of the engine’s water neck (not all DR-Z400S bikes have this screw; if your water neck points straight up, you may not have it, which is common for U.S. DRZ400S models). If present, loosen a few turns for bleeding air as you fill.
  6. Open Bleed Screw on the Radiator: There is an additional air bleed screw on the left radiator top tank. Loosen this a few turns as well.
  7. Refill Coolant: Pour fresh pre-mixed coolant into the right radiator very slowly. As you pour, air will escape from the bleeder screws. Once coolant flows steadily from the water neck's bleed screw, snug it closed. Keep filling; when coolant emerges from the left radiator bleed screw, snug that one as well.
  8. Expel Remaining Air: Gently lean the bike far left and right a couple times–this encourages air pockets to surface at the fill neck. Top off the radiator again if the level drops.
  9. Reinstall the Radiator Cap: Secure the radiator cap (and the retaining screw if you prefer).
  10. Run the Engine: Start the bike and let it idle until it reaches normal operating temperature. Keep an eye on the temperature; if it rises quickly, shut off the bike–there could be a trapped air pocket. Let the engine cool again, open the radiator cap carefully, and top off as needed.
  11. Fill the Overflow Bottle: Add approximately 1 inch of coolant to the overflow reservoir if low. This step helps monitor levels and catch overflow on aggressive rides.
  12. Double-Check for Leaks: After a short ride, let it cool and check coolant level again. Inspect all bolts for tightness and look for any leaks.

Special DR-Z400S Notes

  • The 2010 DR-Z400S may not have a water neck bleed screw; this is normal and does not affect cooling system refilling. Just use the left radiator bleed screw and lean the bike as described.
  • Suzuki does not use an automatic air-bleed port or thermostat in most DR-Z400S models. Manual air purging during the fill process is crucial to avoid overheating.
  • Avoid mixing standard green coolant with silicate-free motorcycle-specific coolant. Always use the type specified in your owner’s manual for aluminum radiators/full compatibility.
  • If the coolant you drain is especially dirty or discolored, consider flushing the system with distilled water before refilling.
  • The radiator guards and plastic covers are sometimes difficult to realign. Take your time on reassembly to avoid cross-threading bolts or stripping plastic mounting tabs.

When to Change Coolant

Change at least every two years or 7,500 miles, but more often if you ride deep mud/harsh desert or after flooding the bike.

Ready for Your Next Ride?

Routine coolant changes keep your engine protected and at the right temperature. For gaskets, caps, or fresh coolant, shop parts for a 2010 Suzuki DR-Z400S Dirt Bike.

Related Shopping Categories

Shop Radiators for a 2010 Suzuki DR-Z400S Dirt Bike.

Shop Coolant for a 2010 Suzuki DR-Z400S Dirt Bike.

Shop Temperature Sensors for a 2010 Suzuki DR-Z400S Dirt Bike.

Shop Tools for a 2010 Suzuki DR-Z400S Dirt Bike.

Shop Radiator Hoses for a 2010 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.