GM made significant changes to its truck engines in 2011 to keep up with ever-changing emission standards as well as to keep pace with Ford’s upcoming 6.7L Powerstroke. This was the sixth generation of the diesel engine and was given the RPO code LML. It wasn’t a full redesign since the engine still displaced 6.6L, had a 16.8:1 compression ratio and used a cast-iron block with aluminum heads. And yet, the changes that were made were the most extensive Duramax had ever attempted. +Read more
First, the common rail injection system was updated. It was equipped with the latest high-pressure fuel pump (30,000 psi) and injectors from Bosche. In addition, a selective catalytic reduction (SCR) system was included to help better control NOx emissions. GM also added a ninth injector which helped eliminate the oil dilution problems connected to the soot burning regeneration process found on the LMM diesel engine. The result was a powerhouse engine that produced 400 horsepower and 765 lb-ft of torque.
Thanks to the new technology provided by its variable vane turbocharger, a factory provided exhaust brake was available for the first time on a GM truck. GM also upgraded the pistons and lightened the rotating assembly.
For all intents and purposes, the Duramax LML appeared to be the ultimate Duramax diesel engine to date and in many cases it was. The fuel economy was up thanks to the SCR system. Power was up thanks to the new injection components and the LMLs towing performance was unequaled by Ram or Ford.
However, after a while, it began to have problems with the injection pump due to poor maintenance or bad fuel, the turbocharger had the smallest variable geometry unit at the time and the components of the emissions system (DPF, EGR, SCR) were all susceptible to unforeseen issues.
If those, or any other problems have your Duramax LML running poorly, ProSource can help. We are the professional mechanics source for OEM and aftermarket diesel parts. Give your Duramax engine top performance with 6.6L LML parts from ProSource.