The engine accessories on the Lexus ES 300 model vehicles are operated by a single multi-ribbed serpentine belt. The engine accessories include the power steering pump, air conditioner compressor, water pump and the alternator. The ribs on the inside of the belt travel in the grooves of each accessory pulley. When the engine is running, the belt turns around each pulley so each accessory can perform its required task. Once the belt becomes frayed or cracked within the belt ribs, change it immediately.
Raise the hood and locate the belt routing diagram for the serpentine belt. The diagram should be stamped to the top surface of the fan shroud. Route the new serpentine belt by following the exact routing instructions from this diagram.
Locate the serpentine belt self-adjusting tensioner on the front of the engine. The tensioner has an idler pulley connected to the bottom of the tensioner arm. The tensioner can only be turned from the bolt in the middle of the idler pulley.
Turn the tensioner from the idler pulley bolt counter clockwise with a metric socket and a breaker bar. The socket size should be a 13 mm or a 14 mm.
Pull the belt off the idler pulley and release the tensioner. Pull the belt off the other accessory pulleys.
Pull the belt up out of the engine area and match it to the new belt. Make sure the new belt has the proper width and length compared to the old belt.
Slide the new belt around the crankshaft pulley on the bottom of the engine. Use the belt routing diagram to properly route the new belt around the other accessory pulleys.
Turn the tensioner counter-clockwise from the idler pulley bolt again. Slide the belt around the idler pulley and release the tensioner. Look over the belt carefully to make sure it is secure inside all the accessory pulleys.
Crank the Lexus ES 300 and let the motor run for about 10 seconds so the turning of the pulleys can completely seat the new belt into each accessory pulley. Turn the engine off and shut the hood.
