BMW N62

The V8 that replaced the M60 / M62 — 3.6 to 4.8 litres, in the E60 5 Series, E63 6 Series, E65 7 Series and both the E53 and E70 X5. It was the first BMW V8 with Valvetronic, throttling on valve lift rather than a throttle plate, and that system is one of the things that goes wrong with it: the eccentric shaft sensor and the Valvetronic motor both fail, and the engine then runs on the limp-home throttle with a marked loss of response.

Two of its faults are famous for costing far more than the part, and both are worth knowing before an estimate arrives:

The alternator bracket gasket leaks, and reaching it is an engine-out or near-engine-out job on most installations. Oil appears at the front of the engine, the part is inexpensive, and the labour is not.

The coolant transfer pipe runs through the vee, under the intake manifold, and its seals fail. Coolant then disappears with no visible external leak, which is exactly the symptom that gets misread as a head gasket. A steady coolant loss on an N62 with a clean exterior and no oil contamination is this pipe, and the repair is a large one.

Beyond those, valve stem seals harden and produce a puff of blue smoke on start-up after the car has stood, and the timing chain guides age as they do on the M62.