I've already asked this question some time ago but I thought I'd try again. My k20 engine with just over 100k on the clock (miles) has a slight tapping noise mainly when it's cold. It's very slightly tapping when it's warm. I have replaced a faulty exhaust camshaft (one lobe was breaking up) I also changed the chain and tensioner as a matter of course. The valve clearances are correct the engine runs very well and it doesn't use any oil. It was suggested it could be piston slap as the tapping noise is in time with the piston stroke. The tapping us pronounced when the engine is slightly under load. Any thoughts or ideas would be greatly appreciated.

 

Noises are tough to figure out over the web. I've read that valves can make some tapping noise when cold, then the noise reduces when the engine warms up.

Not sure if there is much you can do without tearing apart the engine to verify piston slap.