The 2024 GMC Sierra HD is include in an urgent service update recently issued by GM, which offers a fix for an engine coolant contamination problem that leads to certain units of the truck needing replacement of hoses and the radiator surge tank as well as a complete coolant flush.
Only 2024 GMC Sierra HD units motivated by the optional 6.6L V8 L5P turbodiesel Duramax engine rated at 470 horsepower and 975 pound-feet of torque are affected by the issue and service update. However, certain 2024 Chevy Silverado HD trucks are also included.
2024 GMC Sierra HD trucks brought to the dealer for any reason should be inspected by dealership service personnel for the coolant contamination issue, per General Motors service update number N232430450. Both new and used Sierra HD units in dealership inventory should also be inspected the remedy applied if necessary prior to the demonstration, trading, sale or delivery of the pickups.
The first stage of the repair is to inspect Sierra HD units with the L5P turbodiesel engine to see if a “film of oily black substance floating on top of the coolant” is visible in the surge tank. Presence of this film indicates that the coolant of the truck is in fact contaminated and that the service department should proceed to the second stage.
Before the second stage repairs can be carried out, the dealership must order and receive a new surge tank, heater inlet and outlet hoses, radiator inlet and outlet hoses, surge tank inlet and outlet hoses, and the engine coolant air bleed hose and pipe. Once these components are available, a second service visit should be scheduled to replace the listed parts and complete a coolant flush.
The dealership should set aside a minimum of 11 working hours to carry out the fix, including both the engine coolant parts replacement and the necessary coolant flush. The fix is offered free of charge through the New Vehicle Limited Warranty period for the affected 2024 GMC Sierra HD pickup trucks.
Under the skin, the 2024 Sierra HD is underpinned by a more-capable variant of the GM T1 platform. Production of the pickup model is carried out exclusively at the GM Flint Assembly plant in Michigan.
Comment
How is oil getting into the coolant?