The Pontiac Grand Prix has a long history in the GM line. It started out as a two-door luxury-performance car in 1962, and was last produced in 2008 as a mid-size four-door. In 2002, the 3.1-liter Grand Prix SE was billed as a fuel-efficient family car with sharp handling. The sixth-generation of Grand Prix spanned from 1997 to 2003.
Park your Grand Prix on a solid, level surface. Place wheel chocks behind the rear wheels. Raise the front end by placing a floor jack under the front crossmember. Position jack stands under the pinch welds just behind the front wheels on both sides. Lower the vehicle onto the jack stands.
Let the engine cool completely. Remove the coolant pressure cap. Place a drain pan under the radiator drain petcock, at the bottom passenger-side of the radiator. Loosen the petcock by hand. Drain about a gallon of coolant. Tighten the petcock by hand. Lift the vehicle off of the jack stands, remove them, and lower the Grand Prix to the ground.
Disconnect the the wire connectors from the two sensors on the air intake duct, between the air cleaner housing and the throttle body. Remove the PCV hose from the duct. Loosen the clamps on both sides of the duct and remove it.
Find the thermostat housing by following the upper radiator hose. Loosen the radiator hose clamp with a screwdriver -- or if it is a spring-type clamp, using slip-joint pliers. Twist the hose to break it loose and remove it from the housing.
Remove the top thermostat housing bolt with a socket and ratchet. Loosen the bottom bolt until the housing moves freely. Remove the housing and thermostat. If the O-ring doesn't come off with the thermostat, make sure you remove it from the housing.
Clean any dirt or debris from the housing mating surfaces with a clean rag. Install the new O-ring on the new thermostat. Install the thermostat in the engine side of the housing. Guide the bolt slot in the housing under the bottom bolt that you loosened while removing it. Install the top housing bolt. Tighten the two housing bolts to 18 foot-pounds with a torque wrench.
Install the upper radiator hose and clamp. Install the air duct and tighten the clamps. Connect the two wire connectors the the sensors. Install the PCV hose.
Open the bleeder screw on the thermostat housing with a screwdriver. Fill the cooling system with a 50-50 mixture of Dex-Cool coolant and water until it starts to come out of the bleeder screw. Tighten the bleeder. Start the engine and let it run until the top radiator hose gets hot. Top off the coolant reservoir to the "full hot" line. Install the coolant pressure cap.
