1998 GM Vortec Engine Coolant Sensor

Introduction

This tutorial provides step-by-step instructions for replacing the coolant sensor on late-1990s GM engines, specifically for vehicles like the 1997 Chevy “Smashtro” van and the 1998 Chevrolet Astro. Understanding how to perform this replacement can help maintain your vehicle’s cooling system effectively.

Step 1: Ensure Safety

• Park the vehicle on a level surface.
• Allow the coolant and radiator to cool down to prevent burns or injuries.
• Disconnect the negative battery cable to avoid accidental engine startup while working.

Step 2: Remove Air Intake Assembly

• Unclip the two wiring connectors attached to the air intake assembly.
• Carefully remove the air intake assembly from the vehicle.
• Take off the upper radiator shroud to gain access to the coolant sensor.

Step 3: Access the Thermostat Housing

• Loosen the upper radiator hose clamp located at the engine intake (thermostat housing).
• Twist and pull the engine end of the hose off the thermostat housing.
• Place the hose out of the way to create more working space.

Step 4: Disconnect Additional Wiring

• Locate and unclip the two wiring connectors near the thermostat housing.
• This will help in accessing the coolant sensor without obstruction.

Step 5: Remove Water Pump Hose

• Loosen the water pump hose clamp.
• Pry or pull the water pump hose off the water pump and place it out of the way.

Step 6: Replace the Coolant Sensor

• Use a 3/4" half-inch drive socket to remove the coolant sensor from its housing.
• Install the new coolant sensor by threading it into the same location.

Step 7: Reassemble Components

• Reverse the disassembly steps:
  • Reattach the water pump hose and secure it with the clamp.
  • Reconnect the two wiring connectors near the thermostat housing.
  • Reconnect the upper radiator hose to the thermostat housing and tighten the clamp.
  • Reinstall the air intake assembly and upper radiator shroud.

Step 8: Reconnect Battery

• Finally, reconnect the negative battery cable to complete the process.

Conclusion

Replacing the coolant sensor is a straightforward task that can enhance the performance of your vehicle's cooling system. After completing the replacement, monitor the engine temperature and coolant levels to ensure everything is functioning correctly. If you encounter any issues, consider consulting a professional mechanic.