The engine's timing chain assembly is made up of a lower chain that links the crankshaft sprocket to an idler sprocket on the cylinder head, and also an upper chain which connects the idler sprocket to both camshaft sprockets. Occasionally, replacing such timing chains is a complex process since they are usually meant to last for as long as the engine remains operational; doing so would require removal of the oil pan. To remove the upper timing chain, drain coolant system, removing valve cover, power steering pump, upper idler pulley and camshaft sprockets. Then move on to the lower timing chain by firstly removing the upper timing chain. Remove distributor, various hoses and crankshaft pulley/vibration damper while ensuring that engine remains at TDC for No. 1 piston throughout. If desired, drain engine oil as well as remove oil pan and oil pump pick-up. Take away lower timing chain cover, tensioner arm, tension arm guide piece, oil slinger and oil pump drive gear. In order to make head removal more convenient however, note that it's best in such cases to trim off the head gasket flush with cylinder head surface. Examine parts for wear or damage before installation by matching silver-colored link on lower timing chain with crankshaft sprocket mark and attentively following each step involving both idler sprocket (s), chain guide (s), tensioner arm (s) as well as tensioner (s) in order to ensure correct tensioning. Apply RTV sealant letting it cure prior to securing upper timing chain cover into its position together with installing all necessary components involving camshaft sprockets above: then fill fluids back in followed by running engine slowly looking out for possible leakages.
