Wear from high mileage, lack of oil changes or abuse could cause that.
Well the 2300 is an overhead-can set up. Which means it doesent have push rods or lifters. The cam is what actually pushes the valves open and closed. The cam is set right under the valve cover.
if it is the z32 model more than likely its the variable timing sprocket
Sometimes the Timing belt tensioner will cause a tap or click until the engine is warm.
Taps and dies are used to thread . A tap threads a hole and a die threads a rod.
Further diagnoses is required. A tap from the upper area of the engine indicates valve work. A hammer from the lower end indicates bad bearings (mains or rods). I would check for correct oil pressure first. A failed oil pump may be the problem.
YES
They are usually ceramic disc's in gate valves , best thing is to buy the whole tap hat for it.
Why? sometimes it has a leak, or the pipes are loose, or even some times there is extra water in the fosset that drips out.
Tap water from your house
lifters mate
were the valve tappets adjusted correctly they need to be rotated during adjustments ,also make sure you have correct viscosity oil in engine. it has hydraulic lifters and if oil is cheap, it will aerate and cause rattling
If the valves are ticking they are likely damaged. If what you hear is lifter tap, then it is due to poor design from the factory or you need an oil change. Lifters from a 3g Eclipse (00+) fix this problem.