Volvo B8444S

Volvo's 4.4 V8 — in the XC90 and S80.

⚑ It was designed and built by Yamaha, which is the single most useful fact about it: it is not a Volvo engine in any sense that helps, and Volvo experience, Volvo parts logic and Volvo forum results all mislead. It is also unusually narrow — 60° rather than 90° — because it had to fit transversely in a car designed around a straight six.

That packaging is most of the ownership story. Everything is difficult to reach, the rear bank is against the bulkhead, and jobs that are routine on a longitudinal V8 are body-off work here.

Its known items are the variable valve timing units and the PCV system, both oil-condition dependent. A rough idle, a cam-timing code or oil in the intake is an oil-history question first — the ventilation system blocks and then pressurises the crankcase, which pushes oil past the seals.

Parts are scarce and specific, and that is usually what decides whether a fault is worth chasing on a car of this value.