If the problem is lifter tapping immediately after cranking the engine, the oil check valve in the cylinder head may need cleaning. Page 17-10 in the shop manual covers the procedure.
The check valve is simply a spring-loaded ball in the oil feed line that prevents oil from draining back while the engine is not running. If this check valve doesn't do its job, the oil lines in the head will be empty, and they will require a few seconds to fill when the engine is started, causing lifter tapping.
The valve is located inside the valve cover, at the lower front corner of the head. After pulling the valve cover and finding the valve, locate the locking screw]\ that goes in from the outside of the head to the side of the valve, and loosen it about four or five turns. Screw (by hand) an M6x40 bolt gently into the valve spring guide (the only part that you can see) until it bottoms, then unscrew it two turns. Pull the spring guide out. Using a magnet, remove the spring and ball. Clean everything, being especially careful to avoid damaging the ball seat down in the hole. The book says to replace the o-ring, and it would be a good idea to do so, especially if it is hardened.
Reassemble. The threaded rod that screws into the side to retain the valve should be tightened to 2.8 ft/lb, which isn't much!
If you do this, there would obviously be a lot of WYAITs (While You Are In There, to our newer members), such as new valve cover gaskets, a careful inspection, etc.
Wally Plumley
928 Specialists
