Nissan KA24 (KA24E / KA24DE)

Nissan's 2.4 four — KA24E with a single camshaft and twelve valves, KA24DE with two camshafts and sixteen — in the 240SX, Altima, Frontier and Navara, Xterra and Pathfinder. A workhorse with a long afterlife, because the 240SX made it one of the most swapped engines in the world.

Its defining fault is the timing chain, and it announces itself. The guides are plastic and the tensioner wears, so the engine develops a rattle at the front that is loudest cold and quietens under load. Left alone the guides break up and the chain wears the cover, which turns a manageable job into a much larger one. A rattling KA is a chain job now, not later.

The exhaust manifold cracks — common enough on the KA24DE to be a pattern rather than bad luck — and presents as a ticking that sounds like a valvetrain noise when cold and fades as the metal expands.

Beyond those it is a straightforward engine: the distributor on the KA24E wears and produces a heat-related stumble, and both suffer the usual crankcase ventilation blockage at high mileage.