Chevrolet LN2 (2.2 OHV)

GM's 2.2-litre pushrod four — the S-10, Sonoma, Blazer, Cavalier, Sunfire, Century and Lumina. The engine the 2.2 Ecotec replaced, and nothing about the two transfers: this one is an overhead-valve design with a timing chain and a cast-iron block, and its successor is an all-aluminium twin-cam. Establishing which is fitted is the first step on any 2.2 GM of that period.

It is simple and long-lived, which is most of why so many survive. An engine of this family running badly is very often its ignition module, its crankshaft position sensor or a vacuum leak rather than anything internal.

Its own failure is the head gasket, and it presents in the ordinary way — overheating, coolant loss, and eventually combustion gases in the cooling system. It also shares the GM-wide intake manifold gasket, the composite gasket the 3.1, 3.4, 3.8 and 4.3 all use, which works loose as the engine heats and cools until coolant escapes or gets into the oil.