GM Service Manual Online
For 1990-2009 cars only

Engine Block

The engine block is cast iron. The engine block has four cylinders arranged in-line. The engine block is a one piece casting. The cylinders are encircled by coolant jackets.

Cylinder Head

The cylinder head is cast aluminum made in a lost-foam casting process. This results in a casting requiring very little final machining. The cylinder head has sintered powdered metal valve guides and valve seats.

Crankshaft

The crankshaft is cast nodular iron. Five crankshaft bearings support the crankshaft. The bearings are retained by bearing caps. Number four crankshaft bearing also serves as the crankshaft thrust bearing. The bearing caps are machined with the block for proper alignment and clearances. The bearing caps are retained by two bolts each. Four connecting rod journals are spaced 90 degrees apart. There is one connecting rod on each journal.

Piston and Connecting Rod Assemblies

The pistons are cast aluminum. The pistons use two compression rings and one oil control ring assembly. The piston is a low friction, lightweight design with a flat top and barrel shaped skirt. The piston pins are chromium steel. They have a floating fit in the piston and are retained by a press fit in the connecting rod. The connecting rods are forged steel. The connecting rods are machined with the rod cap installed for proper clearances and alignments.

Camshaft

The camshaft is steel. The camshaft is supported by five bearings pressed into the engine block. The camshaft is of an assembled design with each lobe, journal, and the oil pump drive gear assembled onto a hollow tube which is then expanded to hold the components in place. The camshaft timing chain sprocket mounted to the front of the camshaft is driven by the crankshaft sprocket thorough a camshaft timing chain.

Valve Train

The LN2 valve train utilizes cast steel rocker arms with a roller bearing fulcrum. Motion is transmitted from the camshaft through the hydraulic roller valve lifters and the tubular pushrods to the valve rocker arms. The valve rocker arm pivots on a roller bearing in order to open the valve. The valve train is of the net-lash type without provision for manual adjustment. All valve train lash is taken up by hydraulic roller valve lifters.

The valve springs are of a conical type which reduce valve train harmonics and noise.

The valve seals are integral with the valve spring seats.

Intake Manifold and Fuel Rail

The intake manifold is constructed of a composite material incorporating metallic compression limiters at the mounting points for the throttle body, fuel rail, and the manifold to cylinder head flange. The fuel rail is of an assembled tubular design.

Exhaust Manifold

The exhaust manifold is cast iron.