The head gaskets on the 6.6L LML Duramax (2011–2016) are multi-layer steel (MLS). They’re built to handle high pressure and heat from the turbocharged diesel engine. These gaskets seal the cast iron block to the aluminum heads, keeping oil, coolant, and combustion gases in place.

LML gaskets are stronger than those in earlier Duramax engines. They’re thicker and have special coatings to seal key areas like coolant ports and cylinder bores. Proper torque and new head bolts are key to getting a reliable, leak-free seal.