Lexus 13568-29025 Belt, Timing

To begin the removal process, start by disconnecting the negative battery cable and ensure the rear wheels are blocked while the parking brake is engaged. Loosen the lug nuts on the right front wheel, raise the vehicle, and securely support the front on jackstands. Proceed to remove the right front wheel and fender apron seal. Following this, remove the coolant overflow tank and the spark plugs and drive belts. Take out the alternator and its bracket and support the engine from beneath with a jack (using a wood block to avoid the oil pan drain plug). Remove the right engine mount and engine support rod. Afterward, remove the upper timing belt cover screws and pull up the wiring harness, then remove the upper (no.timing belt cover and gaskets. Ensure the number one piston is at TDC on the compression stroke and verify alignment between the small hole in the camshaft pulley and the TDC mark on the cam bearing cap. Optionally, apply match marks on the sprocket and belt if reusing the timing belt. Loosen the upper (no.idler pulley set bolt and unhook the spring to slip the timing belt off the sprocket. If the camshaft sprocket requires removal, hold the rear camshaft with a wrench and remove the bolt. Remove the crankshaft pulley bolt, secure the engine from turning, and use a breaker bar and socket to loosen and remove the pulley. Proceed to remove the lower (no.timing belt cover and gaskets, slipping the belt guide off the crankshaft if needed. If reusing the timing belt, apply match marks on the sprocket and belt. Slip the timing belt off the sprocket and remove it. Inspect the idler pulleys for smooth operation and the spring for damage, and assess the belt for cracks, wear, or damage. Replace the timing belt with a new one if wear or damage is evident or if there are concerns. When installing the new belt, ensure the timing marks on the camshaft and crankshaft are correctly aligned. Reinstall idler pulleys and the tension spring, check timing mark alignment again, and fit the timing belt onto the appropriate components. Slip on the belt guide with the cupped side facing out and reinstall the lower timing belt cover and crankshaft pulley, verifying TDC marks. Place the timing belt over the camshaft sprocket while maintaining tension on one side, loosen the upper idler pulley bolt, and allow the spring to apply pressure. Slowly turn the crankshaft clockwise until the marks align correctly, then tighten the idler pulley. Rotate the crankshaft two revolutions and recheck the timing marks. If they align as required, reinstall the remaining components in reverse order, paying attention to gasket material on covers if necessary. Finally, run the engine to verify proper operation.

Positioning the number one cylinder at Top Dead Center (TDC) is important because it sets the engine in the correct position for timing belt removal and installation.