Isuzu introduced the Rodeo in 1990. The 2000 Isuzu Rodeo was equipped with the option of a 2.2-liter in-line 4-cylinder engine, or a 3.2-liter V-6. The thermostat on the 2000 Rodeo engines controls the engine's internal temperature, through regulation of the flow of coolant. Thermostats can go bad or stick shut over time. The only difference between the thermostat replacement on the two different engines is that the 2.2-liter has 2 thermostat housing bolts, and the 3.2-liter engine has 4 thermostat housing bolts. The procedure for changing the thermostat on each engine is otherwise identical.
Raise the hood of the Rodeo and set the hood prop, in order to support the hood for this entire project. Visually inspect the top front of the engine and locate the thermostat housing. The housing will have a small heater hose or coolant hose protruding from it. Place a radiator hose clamp or needle nose pliers around the heater hose to stop the flow of coolant through the hose.
Place a certified automotive drain pan beneath the engine, directly under the thermostat area. Loosen the heater hose clamp with a 3/8-inch drive ratchet and socket. Remove the hose from the inlet completely, and aim the open hose end directly into the drain pan beneath the Rodeo.
Remove the two retainer bolts from the thermostat housing, using a 3/8-inch drive ratchet and socket along with a 4-inch or longer extension. The addition of an extension between the ratchet and socket will allow for greater reach and leverage while removing the bolts, while leaving you more room to maneuver the ratchet. Turn the bolts counterclockwise until you have removed them from the engine and thermostat housing.
Remove the thermostat housing with one hand. Remove the thermostat from the engine and place it directly into the drain pan beneath the engine. Do not discard of the thermostat onto the ground.
Place a light film of RTV silicone sealant on the engine mounting surface for the thermostat housing. Install a new thermostat gasket onto the new thermostat. Install the two new components into the engine mounting area, by hand. Install the thermostat housing directly over the new thermostat and gasket. Tighten the thermostat housing bolts to 11 foot-pounds, using a certified 3/8-inch drive torque wrench and socket.
Install the heater hose back onto the water inlet on the thermostat housing. Tighten the hose clamp until it is snug, and then turn the 3/8-inch drive ratchet and socket 1/4-turn farther. This "snug-and-a-quarter" tightening method will place enough torque on the hose clamp, without damaging the cooling system parts.
Remove the radiator cap from the Rodeo. Place a radiator hose clamp or needle nose pliers around the upper radiator hose, in order to stop the coolant flow and increase pressure. Start the engine and let the engine run for no less than 15 minutes.
Turn the heater control panel switches to full fan speed, full heat and front defrost. This will heat the engine quicker. The purpose of this exercise is to force the air pockets out or bleed the cooling system. Air pockets in the cooling system can apply excessive heat to portions of the engine, causing severe damage. Turn the engine off when there are no more air bubbles coming from the radiator. Refill the radiator using 50/50 premixed universal coolant. Replace the radiator cap when the radiator is full.
