Q: How to Remove and Install a Timing Chain and Variable Timing Sprocket in a 4.6L and 5.7L Engine on a Toyota Sequoia?
A: The timing system is slightly involved and drastic engine damage could result in the case of a misunderstanding, this should only be carried out by experienced personnel in consultation with the mechanic in case of difficulties. Start with live electromagnetic termination of the negative companion terminal, eliminating fuel pressure and removing fuel hoses. Before proceeding with the work, you must drain the engine oil and coolant, disconnect the engine cover, the fan shroud and the radiator, the inlet duct and the housing of the air filter. Most connections are disconnected electrically; the intake manifold, heater hoses, thermostat housing, water pump, and the A/C compressor are some of the parts, which can be pulled out of the way only in some cases. Put off the oil filter, the dipstick tube, power-steering pump, the alternator, the fan bracket assembly, the ignition coils, spark plugs, and both the valve covers. Leave the engine to remain on TDC, aside from that, loosen the crankshaft pulley and take the timing chain cover off without scratching the cover. Remove the old crankshaft seal and as far as the piston in No. 1 cylinder is nearing the TDC on the compression stroke to check the crankshaft and camshaft timing marks on the sprockets. Fasten the No.1 tensioner with the retracted position, take out the chain vibration dampers and notice the timing marks before taking off the No. 1 timing chain and crankshaft timing chain sprocket. Tighten the No. 2 chain tensioner and shut the lock, then remove the camshaft timing sprockets and No. 2 tensioner and put the components in anOne of the sealed transparent plastic bags. Do the same for the No. 3 timing chain as well as the timing chain tensioner; however, do not rotate crankshaft during removal. Check all timing chain assembly components for signs of wear and or damage, and check the length of the chain as well as the diameter of the sprockets and the tensioners. To check it, you should grab the crankshaft when the starter is not engaged and try to rotate it; there should be some level of resistance. Timings for the No.2 timing chain is to position the yellow mark links with the timing lines and finally bolt the sprockets onto the cams. Unbolt No. 1 chain cover, and put the long timing chain in position, with orange links engaging timing dots and then bolt the No. 1 tensioner. Scrape off the earlier applied RTV sealant from the mating surfaces, replace the crankshaft oil seal and O-ring, apply gray RTV sealant to the O-ring and finally place the timing chain cover and fasteners while tightening them in the correct manner. reverse all the procedures mentioned under removal, replace the oil and the coolant, join the battery terminals, and start the engine to search for any fluid leakage.