I have a 2021 Savana with the 6.6l gas. Heard a ticking noise was told it was normal while under warranty. 137000 miles the tick got louder and number 8 cylinder misfire. Replaced spark plug and coil still misfire. Removed intake manifold and valley plate to find a destroyed cam shaft. GM said to many miles on engine and would not warranty. $13000 new engine installed. 30000 miles new engine misfiring on cylinder 1 put new shark plug and coil on sill misfiring. Also have the ticking back. Back to dealer next week
