GM is buying back an unknown amount of both Chevy Silverado and GMC Sierra pickups with diesel engines. It has not indicated the number of trucks involved in the buyback. Also unknown are the years the issue is affecting. What we do know is that the problem involves quality issues surrounding the 6.6-liter L5P V8 Duramax turbo-diesel engine. 

GM issued a Dealer Order Submission on April 21, 2022. It encompasses both fleet and retail buyers of the trucks. Some, but not all, of the trucks have already been purchased. Besides not knowing the years or amount of trucks involved, we also don’t know what the problems are with the Duramax engines. 

Will the GM buyback replacements be 2022 Silverado and Sierra trucks?

GM will replace the trucks with 2022 Silverado and Sierra trucks. The unfortunate part of the buyback is that trucks assembled right now don’t have all of the features previously built trucks have. With the microchip shortage affecting many components used in these vehicles, it is a reminder of the issues affecting manufacturing today. 

So far there are numerous options that are not available. They include heated and ventilated front seats, heated outboard rear seats, heated steering wheel, and front and rear park assist. 

There have been issues off and on with the Duramax for years. The 2003 Duramax has been called out as being problematic. GM first started using the Duramax engine in its trucks in 2001. It stopped production of the 3.0-liter LM2 turbo diesel engine for a few weeks in the latter part of 2021. GM restarted production in November 2021. 

Who makes the Duramax engines for the Silverado and Sierra?

GM produces the Duramax engines at its Flint, Michigan, engine plant. The LM2 turbo diesel has 277 hp and 460 lb-ft of torque. Both the head and block are aluminum, with a forged steel crankshaft, forged rods, iron cylinder liners, and hypereutectic cast aluminum pistons. 

Topside there’s a DOHC valvetrain for managing common rail and direct fuel injection. A liquid-to-air intercooler helps to keep temps down. All of this works to give 23 mpg city, 31 mpg highway, and 26 mpg combined. 

What problems does the 6.6-liter Duramax diesel have?

When it comes to the 6.6-liter Duramax, it offers 445 hp and 910 lb-ft of torque. It’s available with either the six-speed automatic or 10-speed MGM or MGU automatic transmissions. The main problems with the 6.6-liter appear to be fuel injection issues.

Fuel starvation, air getting into the fuel lines, and problems bleeding the system are all known issues. The blame is placed on not having an electric low-pressure lift pump, which moves fuel from the tank to the injection pump. We don’t know if this is the reason for the buybacks. 

Once it becomes clearer what is affecting the engine and which models are pegged for buybacks, we’ll update this post. Information about the buybacks should be available before April 21, 2022, according to GM Authority. Some buybacks have already occurred.