A 300C click and clack

What would casue a ckicking noise (like a sewing machine)under acceleration for the first several miles on a cold morning (50 degrees or below, we live in Louisiana)? Car is 2006 Chrysler 300C with 5.7L Hemi motor, 90,000 miles, all lifters replaced last summer - noise was apparent before new lifters. Dealership is stumpted - they do not believe it is a problem with new lifters.

All the cars I’ve owned have been a bit noisy for the first couple miles on a cold day. I think the oil is just a bit thick and the hydraulic lifters make a little noise. Just take it easy until the engine warms up a little. It takes some heat to expand all the moving parts to their proper operating tolerances. I live in Pittsburgh, where the winters are probably colder than Louisiana, and I just make sure to have 5W-30 in when the cold starts to come around.

A very small exhaust leak will sound like a mechanical “click”.

Was the camshaft checked for wear? Almost every vehicle that I’ve seen that had all lifters replaced had worn camshafts.