The 4.2 is an interference engine, so the timing belt (with water pump, guides) is the periodic must-do. The platform's signature failure is a plastic oil-cooler pipe that rots and leaks — a cheap part but a labor-intensive job — alongside valve-cover seepage and failure-prone window regulators. …
4.2 V8 upkeep: timing belt and the rotting oil-cooler pipe
Audi S6 (C5) · mechanical