Ford Cologne V6

Ford's German-built V6 — in the Ranger, Explorer, Mustang and the Mercury equivalents, and in European Fords for decades before that.

The 4.0 is the one most people meet, and it came in two quite different forms: the older pushrod version and the later SOHC, which share a displacement and a name and very little else.

⚑ The SOHC 4.0's timing chains are its defining fault, and the arrangement is unusual: there are three chains, and two of them are at the BACK of the engine, driven off the rear of the crankshaft. The symptom is a rattle on a cold start that comes from behind the engine rather than in front of it — and the repair means removing the engine or the transmission, which is why a chain rattle on one of these is quoted so high.

Catching it as a noise genuinely matters here, because a guide that has broken feeds debris into the oil.

The pushrod version has none of this and is a simple, long-lived engine whose faults are gaskets and sensors. The model year decides which is in front of you, and nothing on the car says so.