Chevrolet Silverado / GMC Sierra. Service manual — part 217

Fig. 730: Identifying Engine Preluber J 45299
Courtesy of GENERAL MOTORS CORP.

5. Install the flexible hose to the adapter and open the valve.

6. Pump the handle on the J 45299 in order to flow a minimum of 1-1. See Special Tools.9

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.3L - Sierra & Silverado

liters (1-2 quarts) engine oil. Observe the flow of engine oil through the flexible hose and
into the engine assembly.

7. Close the valve and remove the flexible hose and adapter from the engine.

8. Install the gallery plug to the engine.

Tighten: Tighten the oil gallery plug to 60 N.m (44 lb ft).

9. Top-off the engine oil to the proper level.

DESCRIPTION AND OPERATION

CRANKCASE VENTILATION SYSTEM DESCRIPTION

General Description

A crankcase ventilation system is used to consume crankcase vapors in the combustion process
instead of venting them to the atmosphere. Fresh air from the intake system is supplied to the
crankcase, mixed with blow by gases and then passed through a calibrated orifice into the intake
manifold.

Operation

The primary control is through the positive crankcase ventilation (PCV) orifice which meters the
flow at a rate depending on inlet vacuum. The PCV orifice is an integral part of the valve cover.
If abnormal operating conditions occur, the system is designed to allow excessive amounts of
blow by gases to back flow through the crankcase vent into the intake system to be consumed by
normal combustion.

Results of Incorrect Operation

A plugged orifice may cause the following conditions:

Rough idle

Stalling or slow idle speed

Oil leaks

Sludge in engine

A leaking orifice may cause the following conditions:

Rough idle

Stalling

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.3L - Sierra & Silverado

High idle speed

DRIVE BELT SYSTEM DESCRIPTION

The drive belt system consists of the following components:

The drive belt

The drive belt tensioner

The drive belt idler pulley

The crankshaft balancer pulley

The accessory drive component mounting brackets

The accessory drive components

The power steering pump, if belt driven

The generator

The A/C compressor, if equipped

The engine cooling fan, if belt driven

The water pump, if belt driven

The vacuum pump, if equipped

The air compressor, if equipped

The drive belt system may use 1 belt or 2 belts. The drive belt is thin so that it can bend
backwards and has several ribs to match the grooves in the pulleys. The drive belts are made of
different types of rubbers, chloroprene or EPDM, and have different layers or plys containing
either fiber cloth or cords for reinforcement.

Both sides of the drive belt may be used to drive the different accessory drive components. When
the back side of the drive belt is used to drive a pulley, the pulley is smooth.

The drive belt is pulled by the crankshaft balancer pulley across the accessory drive component
pulleys. The spring loaded drive belt tensioner keeps constant tension on the drive belt to prevent
the drive belt from slipping. The drive belt tensioner arm will move when loads are applied to the
drive belt by the accessory drive components and the crankshaft.

The drive belt system may have an idler pulley, which is used to add wrap to the adjacent pulleys.
Some systems use an idler pulley in place of an accessory drive component when the vehicle is
not equipped with the accessory.

ENGINE COMPONENT DESCRIPTION

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.3L - Sierra & Silverado

Balance Shaft

The cast iron balance shaft is mounted in the crankcase above and in-line with the camshaft. A
camshaft gear drives the gear attached to the balance shaft. The front end of the balance shaft is
supported by a ball-type bearing. The rear end of the balance shaft uses a sleeve-type bearing.

Camshaft

The steel camshaft is supported by four bearings pressed into the engine block. The camshaft
timing chain sprocket mounted to the front of the camshaft is driven by the crankshaft sprocket
through a camshaft timing chain.

Crankshaft

The cast nodular iron crankshaft is supported by four crankshaft bearings. The number four
crankshaft bearing at the rear of the engine is the end thrust bearing. The crankshaft bearings are
retained by bearing caps that are machined with the engine block for proper alignment and
clearances. The crankshaft position sensor reluctor ring has three lugs used for crankshaft timing
and is constructed of powdered metal. The crankshaft position sensor reluctor ring has a slight
interference fit onto the crankshaft and an internal keyway for correct positioning.

Cylinder Heads

The cast iron cylinder heads have one intake and one exhaust valve for each cylinder. A spark
plug is located between the valves in the side of the cylinder head. The valve guides and seats are
integral to the cylinder head. The 4.3L heavy duty applications have pressed in exhaust valve
seats. The valve rocker arms are positioned on the valve rocker arm supports and retained by a
bolt.

Engine Block

The cast iron engine block has six cylinders arranged in a V shape with three cylinders in each
bank. Starting at the front side of the engine block, the cylinders in the left bank are numbered 1-
3-5 and cylinders in the right bank are numbered 2-4-6, when viewed from the rear. The firing
order of the cylinders is 1-6-5-4-3-2. The cylinders are encircled by coolant jackets.

Exhaust Manifolds

The cast iron exhaust manifolds direct exhaust gases from the combustion chambers to the exhaust
system.

Intake Manifold

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.3L - Sierra & Silverado