Lexus 13054-20020 Camshaft Sub-Assy, NO.4

Ensure you have two 6 x 1.0 mm bolts. Start by aligning the engine at TDC and removing the valve covers timing belt, and camshaft sprocket. Remove the intake cam and exhaust camshaft for each head, and align cam timing marks. Repeat for the exhaust camshaft. For exhaust camshaft gear disassembly, mount the camshaft in a vise, rotate the sub-gear, and remove the first service bolt. Remove the sub-gear snap-ring, wave washer, sub-gear, and camshaft gear spring. For installation, reassemble the exhaust camshaft gears, align the holes of the gears, and install a service bolt. Apply grease to the lifters, install them in the cylinder heads, and apply lubricant to exhaust camshaft lobes, bearing journals, and gear thrust faces. Install bearing caps and a new camshaft oil seal. Repeat for the other cylinder head. Remove the service bolt, and reinstall the camshaft sprockets and the timing belt.

Before initiating the removal process, ensure you have two 6 x 1.0 mm service bolts (16 to 20 mm long) at hand. To begin, remove the valve cover and the distributor. Proceed to remove the timing belt, camshaft sprocket, and upper rear belt cover. Measure the camshaft thrust clearance (endplay) using a dial indicator, and if it exceeds the service limit, replace the camshaft or cylinder head. For the exhaust camshaft, position the knock pin in the INTAKE camshaft at 10 to 45 degrees left of vertical, securing the exhaust camshaft sub-gear to the main gear with one service bolt before removing the rear exhaust camshaft bearing cap bolts and caps. Loosen and remove the exhaust camshaft bearing cap bolts sequentially and then remove the camshaft. For the intake camshaft, place the knock pin at 80 to 115 degrees left of vertical, remove the front intake camshaft bearing cap bolts, and lift off the caps and oil seal. Loosen and remove the intake camshaft bearing cap bolts sequentially and then remove the camshaft. To disassemble the exhaust camshaft gear, mount it in a vise and install a second service bolt in the unthreaded hole to secure the sub-gear. Rotate the sub-gear clockwise and remove the first service bolt, followed by the snap-ring, wave washer, sub-gear, and camshaft gear spring. Inspection involves measuring the camshaft gear spring's end gap, checking valve lifters and shims, inspecting each lifter for wear, measuring lifter bore oil clearance, examining cam lobes and journals for damage, and checking journal oil clearance. To measure journal oil clearance, clean the bearing caps and journals, lay Plastigage on each journal, install the caps, tighten the bolts in increments, and compare the crushed Plastigage width to specifications. If clearance exceeds the limit, replace the camshaft or cylinder head. For reinstallation, apply moly-base grease or assembly lube to lifters, camshaft lobes, and journals. Follow specific positioning instructions for the intake and exhaust camshafts, apply RTV sealant as needed, secure bearing caps, and install a new camshaft oil seal for the intake camshaft. Reassemble the exhaust camshaft gear, align the camshaft gears' timing marks, install the bearing caps, tighten bolts in increments, and remove the service bolt from the camshaft gear. Complete the process by installing the timing belt pulley, timing belt, and the remaining components in reverse order.