audi s4 timing chain replacement interval
When you hear of chain failure in the S4 motor it is in fact the cam adjusters, chain tensioners, and chain guides that wear out / break. There have been no issues to our knowledge of an actual chain snapping.
you need to replace the timing belt eventually, But that is completely different. the timing chain is a full engine removal. as long as you keep the right oil in the engine and perform regular oil changes, you shouldn't have to worry about the timing chain. i have a '10 S4 with 125k miles and it runs great.
Timing chain: Audi A4 2.0 TFSI quattro 2013 – 2016: 211 hp: Timing chain: Audi A4 2.0 TFSI quattro 2013 – 2016: 225 hp: Timing chain: Audi S4 2013 – 2016: 333 hp: Timing chain: Audi RS 4 2013 – 2016: 450 hp: Timing chain: Audi A4 2.0 TDI 2013 – 2016: 136 hp: 210 000 kilometres: Audi A4 2.0 TDI DPF 2013 – 2016: 143 hp: 210 000
Bumper cover and front clip is only an hour or so, so dropping the engine to get to the rear chains is a curious call. And bunch of other parts. Search for Audi A8 4.2 BVJ timing chain replacement Forum Some info on the cooler/O-rings replacement and other parts to replace while the front clip is off in discussion here within DasuberS8's thread.