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6.6L Duramax LB7

The LB7 Duramax was first introduced for the 2001 model year as General Motors retired its 6.5L Detroit diesel. In every possible way, the Duramax was superior to the outdated Detroit and marked a revolutionary turning point for GMC and Chevrolet pickups in the diesel marketplace. 2001 also introduced the Allison 1000, arguably the first automatic transmission in its class worthy of being mated to a powerful diesel. The LB7 also appeared as the engine to adopt common rail technology, as Dodge would not implement its own common rail Cummins until the 2003 model year and it would take Ford's Power Stroke until 2008 to apply the technology. The LB7 is unique to other Duramax models as it predates emissions regulations. As such, it's praised for reliability and has been regarded as a particularly economical variation of the engine.

The LB7's applications included the Chevrolet Silverado HD, GMC Sierra HD, GMC TopKick (medium duty), and Chevrolet Kodiak (medium duty). As impressive as GM's new engine platform appeared, the LB7 had terrible problems with fuel injectors failing. In fact, injector failures were so frequent that GM was forced to recall the poorly designed units and replace them with an updated design. In order to provide loyal customers with a sense of reassurance, the factory warranty was extended to cover the new injectors for up to 200,000 miles. Despite injector troubles, the Duramax was featured in Ward's "10 Best Engines" for the 2001 and 2002 model years.
Potential buyers were immediately concerned with regard to the Duramax's aluminum heads, and for nearly a decade owners of competitor's pickups would gripe about their distrust for the alloy heads. However, head gasket failures (or other related concerns for that matter) are no more frequent on the aluminum headed Duramax diesel than other competitor's cast iron headed engine. Not only has the head design proven reliable, but other manufacturers have begun to employ aluminum alloy cylinder heads on their diesels in order to benefit from the significant weight saving.
The LB7 was available mated to the Allison 1000 five speed automatic transmission or the ZF 6 speed manual transmission, with the automatic being a much more common choice. The LB7 was produced through the 2004 model year, when the LLY was introduced in its place.

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