Chevrolet 6.5 V8 diesel (L56 / L65)

GM's 6.5-litre V8 diesel — in the GMT400 Tahoe and Yukon and the Express and Savana vans. The engine the Duramax replaced.

⚑ Its defining failure has a name and a part number: the injection pump driver module. The PMD is an electronic module bolted to the side of the injection pump, in the engine valley, where it cooks — and when it fails the engine cuts out without warning and restarts once it has cooled. An intermittent stall on a 6.5 is this until proven otherwise, and the standard repair is to relocate the module to cooler air with an extension harness.

It is an indirect-injection engine and it is not a Duramax. Nothing written about the later engine applies: there is no common rail, the injection is mechanical with electronic control of timing, and the outputs are modest by any modern standard.

Cracked blocks and heads are a known pattern on engines that have been worked hard or overheated, which on a diesel of this age usually means a cooling system that was neglected rather than a design fault.

The naturally aspirated 6.2 that preceded it shares the architecture and much of its parts list, and its results usually apply — except for everything turbocharger-related.