6.6L LB7, LLY Duramax Diesel Engine Cylinder Head Gasket Missing Thickness Grade Markings - Inspect Block for Stampings

A small number of remanufactured engines were built using oversized bore or milled deck gaskets that do not have any thickness grade identification markings. These engines may show up in any model year from 2001-2005 if the vehicle has received an engine replacement.

Inspect the block for stampings (1) indicating cylinder overbore and a milled deck. The overbore gasket accommodates all cylinder bores from 0.010-0.030". All blocks that are milled are also over-bored.

Crimped Construction Style Head Gasket

First generation head gasket crimped construction (1).

Riveted Construction Style Head Gasket

Second generation head gasket riveted construction (1).

Important: The gaskets with no thickness grade specifications will be of crimped construction as opposed to riveted construction. These gaskets require a higher torque specification than what is published in SI. Use the following torque specification when servicing an engine using a head gasket of crimped construction.

Cylinder Head Bolt Torque Specification for Crimped Construction Head Gasket

Refer to Cylinder Head Replacement in SI. Tighten the cylinder head bolts in the following steps using the sequence below:

Tighten

1. Tighten the M12 bolts a first pass to 50 N·m (37 lb ft).
2. Tighten the M12 bolts a second pass to 80 N·m (59 lb ft).
3. Tighten the M12 bolts a third pass to 90 degrees, using Torque Angle Meter J 45059.
4. Tighten the M12 bolts a final pass to 75 degrees, using Torque Angle Meter J 45059.
5. Tighten the M8 bolts to 25 N·m (18 lb ft).

For vehicles repaired under warranty, use: