Hey guys, I have an 07' Avalanche and a 17' Silverado, both with 5.3s, and both tick. It's a largeproblem with the 5-3s. The '17 is so faint, I don't bother, but the avalanche seemed to get louder over 2 years, 1st only with the engine cold, then warm, then constant. I found out that exhaust manifold holds breaking was a 5.3 issue, not having the proper seal and causing engine ticking to become more and more audible. My mechanic told me to just leave it alone because it would cause drilling out the block and machining the exhaust ports (possibly) and revealing gaskets. It's such a big problem that there is an aftermarket bracket made to secure it tighter to the block.