A recurring correction: the B5 S4's 2.7T uses a timing belt (unlike the chain-driven B6/B7 4.2 V8). It's an interference engine, so the belt — typically with the main and auxiliary water pumps — is critical interval maintenance (~every 75k miles / 7 years). …
The 2.7T is a timing-BELT motor, not chains
Audi S4 (B5) · mechanical