I have a 2008 Chevy Silverado 5.3 litre. On cold start it has been making a loud tapping noise. Took it to dealer and they replaced all 16 lifters, but vehicle is still making same noise. Dealer said noise is except able for this vehicle and amount of miles (97K) but never had the noise before. Any suggestions.

 

Sounds like it would be a lifter issue but it could also have been the valves. Check your oil levels and make sure your oil pump is working correctly.

 

I did have the 16 lifters replaced and definitely not the valves. Sound comes from the bottom of the engine