What is the cylinder head installation procedure
for the new GM 6.6L diesel engine?
According to the AERA technical committee, there is a revised cylinder head installation procedure for 2001-2003 GM 6.6L VIN 1 diesel engines. These engines are referred to as Duramax diesels and are a result of a joint venture between GM and Isuzu. This procedure should be used any time the cylinder head is removed and reinstalled and supercedes information found in earlier published service manuals.
It is now recommended that all M12 cylinder head bolts be replaced at the time of cylinder head installation. These bolts have a preapplied molybdunum disulfide coating for thread lubrication. Do not remove the coating or use any additional lubricant. Improperly lubricated threads will adversely affect the bolt torque and clamp load. Improper bolt and clamp load can lead to engine damage.
Notice: The left and right cylinder head gaskets are not interchangeable. Improper placement of the cylinder head gasket will block coolant and oil passages and cause severe engine damage. Three different grade (thickness) head gaskets are available and use is determined by piston projection. The gaskets either have one hole or two holes to indicate the different grades as well as "L" and "R" for left and right banks respectfully.
Selecting the proper gasket is determined by the cylinder with the highest piston protrusion. Follow the steps below to tighten the new cylinder head bolts.
- Tighten new 12 mm bolts in sequence to 37 ft.lbs. (50 Nm).
- Tighten new 12 mm bolts in sequence to 59 ft.lbs. (80 Nm).
- Rotate those bolts in sequence an additional 90