The timing chain covers consist of an upper and lower part. To remove the upper cover, first withdraw the rocker cover and extract the eight bolts securing the upper timing cover to the cylinder head, noting the location of the alternator earth lead under the center right-hand cover bolt. For the lower cover, disconnect the lead from the battery negative terminal, drain the cooling system, and remove the water pump. After removing the upper timing cover, unscrew and remove the timing chain tensioner by unscrewing the plug while maintaining hand pressure against the internal coil spring to prevent it from flying out, then extract the piston and spring. Disconnect the plug and lead from the rear of the alternator, remove the alternator from its mountings after slipping the drive belt from its pulleys, and unbolt the alternator mounting bracket. Remove the cover plate from the lower half of the transmission bell housing and jam the starter ring gear with a large screwdriver or cold chisel. Unscrew and remove the crankshaft pulley nut and pull off the pulley, then unscrew and remove the lower timing cover bolts and withdraw the cover, using a knife blade to separate the bottom edge from the sump gasket to avoid breaking or distorting it, while being cautious of the two locating dowels at the base of the cover. If only the main timing chain is to be removed, this can be done without detaching the sump; however, if the oil pump drive chain is also to be removed, the sump must be detached. Before removing either chain, mark it with a dab of paint or a piece of masking tape to ensure it can be refitted in the original running direction. Remove the chain guide rails after extracting the retaining circlips, and take out the camshaft and oil pump sprockets to release the chains. On some early models, a tensioning sprocket is used instead of a movable guide rail, and the action of the tensioner plunger is identical in both types, allowing the sprocket and tension lever to be withdrawn after extracting the circlips. The crankshaft sprocket can be removed after extracting the Woodruff key and the 'O' ring located behind it, noting that the sprocket is a very tight fit and a suitable extractor will be required.
