Chrysler EHD (3.9 Magnum V6)

Chrysler's 3.9 V6 — the 5.2 Magnum V8 with two cylinders removed, sharing its bore, stroke and much of its parts bin — in the Dakota, Ram and Ram Van.

That relationship is the most useful thing about it. A fault documented on a Magnum V8 describes this engine directly, and a great deal more has been written about the V8 because far more were sold. Read V8 material as being about this engine, not merely adjacent to it.

It shares the V8's intake manifold plenum pan gasket, and the symptom is the same and just as misleading: manifold vacuum draws engine oil straight into the intake, so the car uses oil steadily with a dry engine bay and no smoke. It is a comparatively cheap repair that gets diagnosed as rings for years.

The timing chain stretches enough by high mileage to retard the cam noticeably, and the distributor wears. It is an unstressed engine in a working vehicle, so a running fault is far more often one of those than anything internal.