Tapping Noise only when Engine Cold
 

I get a noise when the engine is cold on my '02 RS, it sounds like a tapping of sorts but goes away in 5-10 min. depending on how cold it is -- and only does this when it's cold.

Any suggestion to help prevent this noise condition?

check for exhaust leak at the exhaust manifold to head connection

Could it be the typical LS1 piston slap?

I didn't know GM put LS1 pistons in the 3.8! ;)

All GM cars have the chance of the good old lifter tap. I am a little surprised yours would have it, Its normally caused by carbon deposits from not so clean oil. But sometimes they just act up cold. Wife's mini van started it around 130K Just cold (under 20 degs). What sucked was I did the intake gasket around 120K. tapping never got any worse, always went away as it warmed up. We ran it till 175K and I traded it because the trans was going.

DOH! (Homer Simpson voice)

Ok, maybe the question should shift to "what causes this tap when it's cold"?

Old lifters, due to wear, have a tendency to leak down when engine is stopped, and have to get pumped back up when the engine is restarted, and will clatter away until they pump back up. In a cold engine the oil thickens up and it takes a while to push through the sludge and get to the lifters. A lighter weight oil such as a 5W something synthetic will flow faster when cold and may even help to clean up some of the sludge.

^ Funny I'm using a full synthetic 5W oil already... Might be time for more regular engine cleaner additive like the Lucas one I have already been using every couple months or so...

Could also mean the lifter has seen better days.