BMW M43

BMW's ordinary four-cylinder of the 1990s — the 1.6, 1.8 and 1.9 M43 — in the E36 and E46 3 Series and the Z3.

It is the plain engine in cars people buy for the badge, and that is the practically useful thing about it: single overhead camshaft, two valves per cylinder, a timing chain, and none of the VANOS machinery that makes the six-cylinder cars interesting and expensive.

Its recurring complaints are age and plastic. The crankcase ventilation valve and its hoses harden and split, which gives a fast or hunting idle and a lean mixture; the coolant expansion tank and the thermostat housing are known to crack; and the profile gasket on the oil filter housing leaks onto the alternator below it.

The timing chain guides are plastic and do wear, but far less dramatically than on the later four-cylinders — a rattle on start-up at very high mileage rather than a scheduled fear.

The M44 1.9 beside it is a different engine: twin-cam, four valves per cylinder, and rather more willing. It is deliberately not aliased to this page — and M44 is refused as a designation entirely, because Porsche used the same three characters for the 944's 2.5 four, which shares nothing with either.