The front engine accessories on the Lexus LS400 are operated by a single serpentine belt. This type of belt is routed around every accessory pulley so that each accessory can operate from one single belt that is driven by the crankshaft. As the crankshaft turns, the serpentine belt turns the accessory pulleys. The serpentine belt has small ribs on the underside of the belt that travel inside of the grooved pulleys. Once the belt is damaged, it will have to be replaced.
Open the hood on the Lexus LS400 and look beside the hood locking latch for the routing diagram that gives the instructions for routing the new serpentine belt. If the diagram is not near the latch, look on the underside of the hood for the diagram.
Remove the plastic cover on top of the radiator by removing the small bolts with the 1/2 -inch drive ratchet and a socket.
Loosen the tension from the serpentine belt by turning the belt tensioner device clockwise with the 1/2-inch drive breaker bar and a socket. The belt tensioner device is on the front center of the engine.
Remove the belt from the belt tensioner device pulley with your free hand. Then, slowly release the tensioner device.
Pull the belt from the remaining pulleys. Then, slide the belt over each fan blade and out of the engine area.
Slide the new serpentine belt over each fan blade and onto the accessory pulleys as instructed by the serpentine belt routing diagram. Be sure always to start with the crankshaft pulley and end with the tensioner device pulley.
Turn the tensioner device pulley clockwise with the pull bar and socket again. Then, put the serpentine belt around the tensioner device pulley. Slowly release the tensioner device pulley, and remove the pull bar from the tensioner and out of the engine area.
Look over the new belt and ensure that it is routed correctly. Then, crank the engine and let it run for about one minute and turn the engine off. Inspect the belt again just to ensure that it stayed within the pulleys with the engine running.
Reinstall the plastic cover back over the top of the radiator. Tighten the bolts with the ratchet and a socket.
