Duramax diesel engines are well-made and powerful, but even top engines can sometimes benefit from an upgrade. If you drive a Duramax diesel engine, here’s a breakdown of what the single best upgrade for your specific Duramax likely is.
2001 – 2004 Chevy and GMC HD: Bosch Injectors
If you drive a 2001 to 2004 Chevy or GMC HD, you likely have a Duramax LB7 under the hood. These engines are known for injector issues that arise from an internal ball seat which isn’t hardened. Aggressive tuning or fuel debris can cause the seat to fail, at which point the engine effectively has an injector that doesn’t turn off.
Because of the injector-related issue, fuel injectors are the most commonly recommended upgrade for this Duramax diesel engine. Bosch injectors are high-quality parts that will withstand aggressive tuning and fuel debris much better.
2004.5 – 2006 Chevy and GMC HD: Turbo Inlet Manifold
The LLY engine that powered 2004.5 to 2006 Chevy and GMC HDs was famous for its oversized turbocharger, which was the largest ever offered on a Duramax diesel engine to this point. The turbo was fitted to a relatively small mouthpiece, however, and the restrictive mouthpiece resulted in higher intake and exhaust temperatures.
Changing that turbo mouthpiece out for a turbo inlet manifold that’s more free-flowing will allow the forced air to enter the engine more easily. This will reduce the engine’s operating temperature and thereby, improve performance.
2001 – 2007 Four-Wheel Chevy and GMC: Gear Pump Upgrade
On 2001 to 2007 four-wheel-drive Chevy and GMC models, indexing tabs can eventually rub a hole in the gear pump housing that’s toward the back of the transfer case. This can lead to immediate failure, as the hole will leak fluid and there’s no warning until the leak develops.
To prevent this issue, you can upgrade any four-wheel 2001 to 2007 model with a gear pump kit that will prevent the rubbing.
2007.5 – 2010 GM HD: Transmission Cooler Lines
The cooler lines on 2007.5 to 2019 GM HDs are notorious for leaking, with many models spouting leaks while the truck was still under warranty and then again not long after the original lines were repaired. Leaks within 50,000 miles of installation are common.
Because the factory-supplied cooler lines on these models are prone to leaking, it’s often wise to replace them with higher-quality aftermarket lines that will last longer. This doesn’t need to be done until the lines begin to leak, though.
2011 – 2016 Chevy and GMC HD: Lift Pump
The LML Duramax diesel engine of the 2011 to 2016 Chevy and GMC HDs was redone to meet higher fuel efficiency standards, and one of the changes was replacing the injection pump with a higher-pressure one. The new pump had tighter tolerances and, as a result, was more prone to failure if there’s debris or a lack of lubrication.
Installing an electric lift pump on this engine can help keep aeration from causing problems with the injection pump and improves reliability.