How to Change the Coolant in a 2009 Suzuki DRZ400SM: Step-by-Step Guide

Shop parts for a 2009 Suzuki DRZ400SM Dirt Bike.

Routine coolant changes keep your 2009 Suzuki DRZ400SM running cool and powerful. The DRZ400SM, beloved in the supermoto world, features a liquid-cooled, single-cylinder engine that thrives when its cooling system is properly maintained. With the right steps and a few basic tools, you can tackle this essential maintenance at home–and protect your supermoto's reliability for many rides to come.

Tools & Supplies Needed

  • Metric socket set (including 10mm and 12mm sockets)
  • Medium Phillips screwdriver
  • Catch pan for used coolant
  • Rags or shop towels
  • Pre-diluted, motorcycle-safe coolant (avoid standard automotive coolant unless explicitly marked as compatible)
  • Funnel
  • Torque wrench (recommended)

Drain the Old Coolant

  • Ensure the bike is cool and on a level surface.
  • Remove the left side panel using a 12mm socket if it obstructs radiator or water pump access.
  • Take off the radiator cap by first removing the small screw that secures it, if equipped. Always loosen the cap slowly to release pressure.
  • Place the catch pan under the water pump on the right side of the engine. Remove the drain bolt (10mm hex) from the water pump cover. Allow all coolant to drain out.
  • Reinstall and lightly torque the drain bolt once drained.

Flush the System (Recommended)

  • If the coolant is dirty or has been neglected, flush the system with distilled water. Fill the radiator, run the engine briefly, then drain as before. Repeat until clear.

Refill with New Coolant

  • Your DRZ400SM uses a two-radiator setup–fill through the right radiator neck, not the overflow bottle.
  • Slowly fill the right radiator with new coolant.
  • If your model features a bleed screw on the water neck (top front of the cylinder head) or the left radiator, open it a few turns. Continue filling until coolant emerges from the bleed screws, then snug them closed. Not all DRZ400SM bikes have these screws, especially if the water neck points straight up.
  • Lean the bike left and right to work any remaining air out of the system. Fill until the radiator stays topped off.

Burp the System, Top Off, and Final Checks

  • Replace the radiator cap and side panel.
  • Start the bike and let it idle, monitoring the temperature carefully. Rev the engine gently to circulate coolant and help remove air pockets.
  • Shut off the engine and let it cool, then recheck the radiator and top off coolant if needed.
  • Add approximately 1 inch of coolant to the overflow reservoir, located near the radiator. This step helps the system operate correctly between temperature cycles.

What Makes the DRZ400SM Cooling System Unique?

  • The DRZ400SM lacks a thermostat and, on most models, does not include a radiator fan. Keep this in mind during hot-weather idling or slow-speed riding–airflow is key.
  • Some SM models do not have a bleed screw on the water neck. If absent, lean the bike side to side and fill slowly to expel trapped air.
  • Use only recommended coolants to avoid premature corrosion of the magnesium water pump cover and internal engine passages.

Pro Tips

  • Never mix coolant types; always flush thoroughly if changing.
  • Inspect hoses, clamps, and the radiator cap for wear at every coolant change.
  • Consider upgrading to a higher-pressure radiator cap or adding an aftermarket fan for aggressive street or track riding.

Staying on top of coolant maintenance helps your DRZ400SM perform at its best–whether you're carving city corners or conquering your local track.

Related Shopping Categories

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Shop Radiator Hoses for a 2009 Suzuki DRZ400SM 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.