Locating the Temperature Sending Unit

• 1). Loosen the two hose clamps on each end of the air intake tube – the plastic tube running from the air filter box to the engine – with a Phillips screwdriver. Pull the tube from the throttle body, then from the mass airflow sensor tube. Remove the air intake tube from the engine compartment.
  
  
• 2). Trace the upper radiator hose from the radiator to the engine until you meet the thermostat housing, the metal tubing connecting the upper hose to the engine.
  
  
• 3). Find the electrical sensor attached to this housing, this is the temperature sending unit.
  
  

Removing and Installing the Temperature Sending Unit

• 1). Raise the front of the Malibu with a floor jack, then position jack stands under the vehicle’s subframe. Lower the vehicle onto the jack stands.
  
  
• 2). Crawl under the front passenger’s side of the Malibu until you have a clear view of the bottom of the radiator. Find the radiator petcock on the bottom of the radiator and position a drain pan under it. Open the petcock by turning it counterclockwise a half-turn with a 1/4 inch drive ratchet to start the flow of coolant.
  
  
• 3). Allow about two inches of coolant to flow from the radiator into the drain pan, then tighten the petcock with a 1/4 inch drive socket.
  
  
• 4). Raise the Malibu off the jack stands with a floor jack and remove the jack stands. Lower the Chevy to the ground.
  
  
• 5). Pry upward on the locking tab on the temperature sending unit with a small flat-head screwdriver and pull the wiring harness from the sending unit. Remove the temperature sending unit with a ratchet and deep-well socket.
  
  
• 6). Apply a thin coat of thread sealer to the temperature sending unit and allow the sealer to cure for the time specified by the sealer’s instructions. Thread the sensor into the thermostat housing by hand, then tighten it to 17 foot-pounds with a torque wrench and deep-well socket. Plug the wiring harness into the new sending unit.
  
  
• 7). Reinstall the air intake tube onto the throttle body and mass airflow sensor, then tighten its hose clamps with a Phillips screwdriver.
  
  
• 8). Unscrew the cap from the coolant overflow tank and pour 50-50 premixed Dex-Cool coolant into the overflow tank until the level reaches the “Full Cold” line on the expansion tank.
  
  
• 9). Tighten the cap onto the coolant overflow tank. Start the engine and hold an engine speed of 2,000 to 2,500 rpm until the engine reaches operating temperature, which is about halfway up the temperature gauge. Allow the engine to sit at idle for about three minutes, then shut the engine off.
  
  
• 10
  
  Allow the vehicle to sit until the engine is cool to the touch. Add more 50-50 premixed Dex-Cool coolant to the overflow tank until it reaches the “Full Cold” mark, if needed.
  
  
• 11
  
  Take the old coolant in the drain pan to a used automotive fluid recycling center for disposal. Many auto parts stores take this old fluid for free.