The engine used in this vehicle is the 7.8L (475 CID). The engine identification number is on the front right hand side (passenger) of the cylinder block. For further information, refer to General Information.

The GM model Duramax®7800 engine is used in the vehicle covered in this manual. The engine is an in-line six cylinder, four stroke, water cooled, direct fuel injection, turbocharged diesel. The charge air cooler is the air to air heat exchange system using a corrugated-fin heat exchanger installed in front of the radiator.

The forged crankshaft is supported by seven precision insert main bearings. The crankshaft thrust washer is located at the number seven crankshaft main bearing.

The connecting rods have precision insert type crankshaft (big end) bearings. The piston pins are retained by snap rings. The pistons have three compression rings and one oil control ring. The pistons are cooled by oil jets. Dry liners are used. The liners have been phosphated (P-Mn method), both inside and outside for long life.

The camshaft is supported by four plain bearings, and is gear driven. Motion is transferred to the overhead valves by shaft type roller valve rocker arms.

The cylinder head may be rebuilt with new valve guides and seats.