GM Service Manual Online
For 1990-2009 cars only

Cylinder Block

The cylinder block is cast gray iron and has four cylinders arranged "In-Line". The casting is a semi-open deck type with deep skirt design.

Crankshaft

The crankshaft is cast nodular iron with eight counterweights. The number five counterweight is also the ignition system reluctor wheel. The main bearing journals are cross-drilled, except #5, and the upper bearings are grooved. The crankshaft has a pressed-on balance shaft drove sprocket. Number three main bearing is the thrust bearing. A harmonic balancer is used to control torsional vibration.

Connecting Rod and Piston

The connecting rods are forged steel, heat treated and shot peened. The connecting rod incorporates the floating piston pin. An oil cooling hole, which indexes once per revolution with the connecting rod oil feed hole, is drilled in the large end of the rod for piston cooling. the pistons are cast aluminum. The piston rings are of a low tension type to reduce friction. The top compression ring is ductile iron with a molybdenum facing and phosphate coated sides. The second compression ring is gray iron. The oil ring is a 3-piece spring construction with chromium plating.

Oil Pan

The oil pan is die cast aluminum. The oil pan includes an attachment to the transmission to provide additional structural support. The balance shaft assembly acts like an oil baffle.

Balance Shaft Assembly

There are two shafts supported on bearing insets in a cast split housing. The balance shaft assembly is mounted to the bottom of the engine block. The longer shaft is chain driven by a sprocket on the crankshaft. The shorter shaft is driven by the longer shaft. The shafts rotate at twice the engine speed. The shorter shaft drives the oil pump which is attached to the balance shaft housing. The housing assembly contains the oil pump pick-up and screen on the bottom of the assembly.

Cylinder Head

The cylinder head is a semi-permanent mold aluminum casting. Pressed-in powdered metal valve guides and valve seat insets are used. The fuel injection nozzle is located in the intake port.

Valves

There are two intake and two exhaust valves per cylinder. The valve springs are conical-shaped to fit inside the valve lifter body. Rotators are used on all of the intake valves. The rotators are located at the bottom of the valve spring to reduce valve train reciprocating mass. Positive valve stem seals are used on all valves.

Camshaft

Two camshafts are used, one for all intake valves, the other for all exhaust valves. The camshafts are cast iron. The intake camshaft had a pressed-in hex insert. The hex inset is used to drive the direct drive power steering pump. The intake camshaft also has the camshaft position sensor lobe cast onto it.

Valve Lifters

Direct acting hydraulic valve lifter are used. The valve lifter body includes a hardened iron contact foot bonded to a steel shell. These lifters are not repairable.

Camshaft Housings and Covers

The camshaft housings and covers are cast aluminum. The camshafts run directly on the housings and covers without bearing inserts.

Camshaft Drive

An inverted tooth chain is used. A hydraulic tensioner and three guides control chain motion. The crankshaft and camshaft sprockets are powdered metal. The coolant pump sprocket, which acts as the timing chain idler sprocket, is steel.

Timing Chain Housing and Cover

The timing chain housing is die cast aluminum. The housing assembly includes the oil fill location. The timing chain cover is laminated stamped steel and retains the crankshaft front seal.

Intake and Exhaust Manifold

The intake manifold is made of composite plastic. The exhaust manifold is cast iron.