How to Change the Coolant in a 2015 Suzuki DRZ400SM

Shop parts for a 2015 Suzuki DRZ400SM Dirt Bike.

Maintaining proper coolant levels and ensuring optimal engine temperatures are critical for the longevity of your Suzuki DRZ400SM. Over time, coolant degrades and loses its ability to protect against overheating and corrosion. This proprietary MotoSport guide walks you through the step-by-step process for changing the coolant in your 2015 Suzuki DRZ400SM, including model-specific tips every owner should know.

What You’ll Need

  • Pre-mixed 50/50 motorcycle coolant (avoid using full-strength antifreeze unless properly diluted)
  • Socket set (notably 10mm and 12mm sockets)
  • Phillips screwdriver
  • Drain pan
  • Rags and safety gloves

Step 1: Preparation

  • With the engine completely cool, place your DRZ400SM on a level surface and secure it safely on a stand.
  • Remove the side panel to access the radiator and water pump area. Use your 12mm socket to detach any fasteners as required.
  • Put your drain pan beneath the water pump cover – this is where the coolant will exit.

Step 2: Drain the Coolant

  • Remove the radiator cap by first loosening the small screw securing it. This breaks any system vacuum and ensures a smooth flow.
  • Locate and remove the coolant drain bolt (typically a 10mm bolt) on the water pump cover. Allow the old coolant to drain fully.
  • Inspect the old coolant; if it appears rusty or contains debris, consider flushing with distilled water before refilling.

Step 3: Air Bleed Points – Special Note for DRZ400SM

  • The 2015 DRZ400SM may feature air bleed screws on the water neck (top front of cylinder head) and/or on the left radiator tank. Not all models have both; check yours.
  • Loosen these screws a few turns only—do not fully remove. Their slot allows trapped air to escape as you refill.
  • If your bike’s water neck points straight up, it likely lacks a bleed screw and thermostat. In this case, use extra care to eliminate air during refilling by gently leaning the bike left and right after filling.

Step 4: Refill With Fresh Coolant

  • Add coolant slowly into the right-side radiator, pausing periodically to allow air to escape via open bleed screws.
  • Watch: when coolant begins to seep steadily from any open bleed points, close that screw.
  • Continue filling until the radiator is fully topped off.

Step 5: Final Bleed and System Check

  • Gently lean the bike to the far left and right for a moment. This helps dislodge remaining trapped air. Top off with coolant if the level drops.
  • Replace the radiator cap securely. Reinstall the small cap screw if desired.
  • Start the bike and let it warm up at idle. Stay near to monitor temperature. After reaching operating temp, shut off and let the bike cool.
  • Once cold, open the radiator cap to check and, if necessary, top off the coolant. Repeat if needed.
  • Ensure there’s about 1 inch of coolant in the overflow reservoir.

Model-Specific Advice for the 2015 DRZ400SM

  • The DRZ400SM’s cooling system is sensitive to air pockets. Take extra time with the lean-and-top-off steps to avoid hot spots or rapid overheating.
  • Factory service manuals often omit the last top-off check after engine heat cycling—don’t skip this critical step.
  • If your bike is ridden hard in mixed conditions, inspect radiator hoses and clamps for degradation during coolant changes.

Coolant Disposal

  • Always dispose of old coolant responsibly. Used coolant is toxic to both people and the environment; take it to an automotive recycling center.

Routine cooling system maintenance on your DRZ400SM keeps you riding longer and stronger. For all service parts, gaskets, quality coolant, and more, MotoSport carries everything you need for a hassle-free coolant change.

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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.