1997 Isuzu Oasis LSFACTORY OEM SERVICE PROCEDURE

Fast Idle THERMO Valve

NOTE: Fast idle thermo valve is adjusted by manufacturer and should not be disassembled.
  1. Remove intake air duct from throttle body. Ensure engine coolant temperature is less than 86°F (30°C). Start engine and allow to idle. Place finger over lower port in throttle body and check for air flow. If airflow exists, go to next step. If airflow does not exist, replace fast idle thermo valve and retest.
  2. Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Verify fast idle thermo valve is completely closed. If valve is leaking, engine idle speed will decrease when lower port in throttle body is covered. If valve is leaking, check engine coolant level and for air in cooling system. If cooling system is okay, replace fast idle thermo valve and retest.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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