The Lexus RX 300 model vehicles come equipped with a single serpentine belt mounted on the front of the engine. The serpentine belt operates all of the front engine accessories. These engine accessories include the air conditioner compressor, alternator, water pump and power steering pump. When the motor is running, the serpentine belt travels around each accessory pulley. This process enables each accessory to function from the same belt. If the serpentine belt becomes excessively cracked or frayed, replace it immediately, before it breaks. If the belt breaks, all of the accessories will stop working.
Raise then hood of the vehicle and secure it with the hood rod.
Look on top of the plastic cover that surrounds the radiator and the fan to locate the serpentine belt routing diagram. The diagram will be stamped on top of the plastic cover. This diagram has the routing directions for the new belt. Be sure to refer to it when routing the new belt around the accessory pulleys.
Locate the belt tensioner on the front of the engine. The tensioner on the Lexus RX 300 model vehicles is located on the front-center of the engine, directly above the crankshaft pulley. The tensioner has a roller pulley that is attached to the bottom of the tensioner arm with a single bolt.
Turn the tensioner device from the bolt head located on the center of the roller pulley, using the breaker bar and a socket, then slide the belt out from under the roller pulley.
Pull the belt out of all of the accessory pulleys and out of the engine area. Match the new belt to the old belt to ensure that the new belt is the proper length and width.
Route the new belt around the accessory pulleys by referring to the serpentine belt routing guide for the routing instructions. Be sure to properly route the belt, and make sure that the belt is completely seated inside each pulley before cranking the engine.
Crank the engine of the Lexus RX 300 for about ten seconds to finish seating the new belt onto each pulley. Turn the engine off and close the hood of the vehicle.
