Changing the Coolant in a 2022 KTM 150SX: The MotoSport Guide

Shop parts for a 2022 KTM 150SX Dirt Bike.

Routine maintenance ensures your 2022 KTM 150SX delivers peak performance at every ride. One critical but often neglected job is changing the coolant, which helps your bike run cool under pressure – and prevents major engine damage from overheating or corrosion. Here's a step-by-step guide specific to your MMY 2022 KTM 150SX.

What You Need

  • New coolant approved for KTM two-strokes
  • Drain pan
  • 8mm wrench or socket
  • Rags for cleanup
  • Funnel
  • Distilled water (if coolant is concentrate or flushing is needed)
  • Torque wrench (optional, for precision)
  • Gloves & eye protection

Preparation

  • Always start with the bike cool to the touch to avoid burns.
  • Stabilize the bike on a stand so it won't tip over with side panels or radiator cap removed.

Step 1 – Remove the Radiator Cap

  • Locate the radiator cap on the left side just behind the front number plate.
  • Twist the cap counterclockwise and remove it to relieve pressure and avoid vacuum lock during draining.

Step 2 – Drain the Coolant

  • Find the coolant drain bolt on the lower water pump cover (right side of engine).
  • Place your drain pan under the bolt.
  • Using an 8mm wrench, slowly loosen and remove the drain bolt. Coolant will flow out – let it drain completely.

Step 3 – Inspect and Clean

  • Inspect the sealing washer on the drain bolt for damage. Replace if necessary.
  • Wipe up any coolant on the frame or engine with a rag.
  • If the drained coolant appears rusty or oily, flush with distilled water and repeat the drain process before proceeding.

Step 4 – Reinstall the Drain Bolt

  • Thread the drain bolt back in by hand and then tighten securely (do not over-tighten; refer to your service manual for the specific torque spec).

Step 5 – Fill with New Coolant

  • Using a funnel, pour new coolant into the radiator fill neck until just below the bottom of the filler neck.
  • If your model has a small bleeder screw on the radiator (not all do), briefly loosen it to let trapped air escape, then retighten once coolant appears.

Step 6 – Bleed the System

  • Squeeze the radiator hoses gently by hand to help dislodge any air bubbles.
  • Add coolant if the level drops after air is removed.

Step 7 – Final Checks

  • Reinstall the radiator cap securely.
  • Start the engine and let it idle for 2–3 minutes, then shut off and recheck coolant level. Add more if needed.
  • Ensure no leaks from the drain bolt or hoses.

What 2022 KTM 150SX Owners Should Know

  • The KTM 150SX features a lightweight aluminum radiator specific to this chassis. Over-tightening the drain bolt or cap can cause damage, so use care.
  • This bike uses a pressurized coolant system designed for high-rpm racing. It is especially sensitive to low coolant levels or air pockets, which can rapidly cause overheating.
  • Regular coolant changes every 1–2 years will keep the system corrosion-free and prevent water pump seal wear. 
  • Only use coolant safe for aluminum engines – check your bottle for compatibility with KTM two-stroke bikes.

Take pride in your bike’s maintenance – a properly flushed and filled cooling system will give your 2022 KTM 150SX the reliability it needs for every moto. For replacement parts, radiators, or high-performance coolant, MotoSport.com has your back with parts guaranteed to fit your ride.

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Shop Radiator Hoses for a 2022 KTM 150SX 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.