Chevrolet Gen III small block (LS, 5.3–6.0)

General Motors' third-generation small-block V8 — the LS1 in the C5 Corvette and the Monaro, the LS6 in the Z06 and CTS-V, and the iron-block truck engines LM4, LM7, LQ4 and LQ9 in the Escalade, Suburban, TrailBlazer, Envoy, SSR and H2.

It replaced a forty-year-old architecture and shares almost nothing with it but the bore spacing — new block, new heads, six-bolt mains, coil-near-plug ignition. A part or a procedure for a small-block Chevy of the previous era does not transfer, which is the first thing to establish when reading anything written about "the Chevy 350".

The knock sensors sit in the valley beneath the intake manifold, and they corrode. Water finds its way into the valley, the sensors fail, and the engine reports knock retard and a check-engine light — on a truck that runs perfectly. It is the commonest fault on these engines and the intake has to come off to reach it, which is why a quoted price sounds disproportionate to the part.

The other recurring items are the oil pump pickup tube O-ring, which hardens and lets the pump draw air rather than oil, and crankcase ventilation drawing oil into the intake. The cold-start knock these engines are famous for is usually piston slap, a characteristic of the design that alarms owners and does not shorten the engine's life; distinguishing it from a genuine bottom-end noise is that it fades as the engine warms.

It is a generation rather than an engine, and the cars listed below run 5.3 to 6.0 litres — the LM4 and LM7 at 5.3, the LS1 at 5.7, the LQ4 and LQ9 at 6.0. The knock sensors in the valley and the oil pickup O-ring are common to the generation, which is what makes the family the useful unit here.