GM Service Manual Online
For 1990-2009 cars only

Cylinder Head and Gasket

The cylinder head is made of an aluminum alloy. The cylinder head uses crossflow intake and exhaust ports. A spark plug is located on the exhaust side of each combustion chamber.

Crankshaft

The crankshaft is supported by the 5 main bearings. The number 3 bearing is the end thrust bearing. The main bearings are lubricated from the oil holes which intersect the main oil gallery on the exhaust side of the engine block.

Timing Belt

The timing belt coordinates the crankshaft and the camshaft and keeps them synchronized. The timing belt also turns the coolant pump. The timing belt and the pulleys are toothed so that there is no slippage between them. There is a tension pulley that maintains the correct timing belt tension. The timing belt is made of a tough reinforced rubber similar to that used on the serpentine accessory drive belt. The timing belt requires no lubrication.

Oil Pump

The oil pump draws engine oil from the oil pan and feeds it under pressure to the various parts of the engine. An oil strainer is mounted before the inlet of the oil pump to remove impurities which could clog or damage the oil pump or the other engine components. When the drive gear rotates, the driven gear rotates. This causes the space between the gears to open and narrow constantly, pulling oil in from the oil pan when the space opens and pumping the oil out to the engine as it narrows.

At high engine speeds, the oil pump supplies a much higher amount of oil than required for lubrication of the engine. The oil pressure regulator prevents too much oil from entering the engine lubrication passages. During normal oil supply, a coil spring and a valve keep the bypass closed, directing all of the oil pumped to the engine. When the amount of oil being pumped increases, the pressure becomes high enough to overcome the force of the spring. This opens the valve of the oil pressure regulator, allowing the excess oil to flow through the valve and drain back to the oil pan.

Oil Pan

The oil pan is mounted to the bottom of the cylinder block. The oil pan houses the crankcase and is made of aluminum.

Engine oil is pumped from the oil pan by the oil pump. After the oil passes through the oil filter, the oil is fed through 2 paths to lubricate the cylinder block and the cylinder head. In one path, the oil is pumped through the oil passages in the crankshaft to the connecting rods, then to the pistons and the cylinders in the cylinder block. The oil then drains back into the oil pan. In the second path, the oil is pumped through the oil passages to the camshaft. The oil passes through the internal passageways in the camshafts to lubricate the valve assemblies in the cylinder head before draining back into the oil pan.

Exhaust Manifold

A single 4-port, rear-takedown exhaust manifold is used with this engine. The exhaust manifold is designed to direct the escaping exhaust gases out of the combustion chambers with a minimum of back pressure.

Intake Manifold

The intake manifold is made of aluminum. The intake manifold is heated by the engine coolant. An air/fuel mixture is transferred through the intake manifold to the engine cylinders for combustion.

Camshaft

The cast-iron camshaft is supported by the 5 bearing surfaces in an aluminum camshaft carrier located on the top of the cylinder head. The camshaft gear is power driven by the crankshaft, using the timing belt.