Mercedes-Benz OM639 (with the OM660, 0.8 and 1.5)
inline-3 · turbocharged · diesel · 2004–2012
Also known as: om639, 1.5 di-d, 1.5 cdi three-cylinder, colt diesel, forfour diesel, om660
The 1.5 three-cylinder diesel of the Mitsubishi Colt and the first Smart Forfour — a Mercedes designation on an engine from the DaimlerChrysler–Mitsubishi joint platform, which is why the same engine wears OM639 in one catalogue and DI-D in another.
Establishing that is most of the value of knowing its name. The Colt and the Forfour are the same car underneath, built in the same factory, and a fault documented on one describes the other exactly — which almost nothing published about either says, because the two were sold as unrelated products by unrelated dealers.
It is a small, hard-worked diesel with the ordinary consequences: the injectors and the glow plugs are the recurring items, and the exhaust-gas recirculation valve clogs. On short journeys the emissions equipment cannot complete a regeneration, which is the duty cycle most of these cars actually saw.
Very few were built and the long-term pattern is thinly documented, which is worth stating rather than borrowing from Mercedes' four- and five-cylinder CDIs. It is not one of them.
⚑ This page declares no displacement, because it holds two. The OM660 is 799 cc and the OM639 is 1,493 cc — nearly double — and a figure, a part or a service quantity quoted for the three-cylinder Smart diesel is worth nothing until somebody says which.
Cars fitted with this engine
4 generations, across 2 makes. From the authored catalogue — an absent car means the catalogue has not reached it, not that the engine was never fitted.
Mitsubishi
Information, not instruction
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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