Chevrolet Silverado / GMC Sierra. Service manual — part 401

Fig. 43: View Of Engine Identification Tag
Courtesy of GENERAL MOTORS CORP.

The engine identification tag is located on the left side of the block. It is on the front edge of the
block.

DIAGNOSTIC INFORMATION AND PROCEDURES

DIAGNOSTIC STARTING POINT - ENGINE MECHANICAL

Begin the system diagnosis by reviewing the Disassembled Views, Engine Component
Description and Lubrication Description and the Drive Belt System Description. Reviewing

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

the description and operation information will help you determine the correct symptom
diagnostic procedure when a malfunction exists. Reviewing the description and operation
information will also help you determine if the condition described to you by the customer is
normal operation. Refer to Symptoms - Engine Mechanical in order to identify the correct
procedure for diagnosing the system and where the procedure is located.

SYMPTOMS - ENGINE MECHANICAL

Strategy Based Diagnostics

1. Perform the Diagnostic Starting Point - Engine Controls before using the symptom

tables, if applicable.

2. Review the system operations in order to familiarize yourself with the system functions.

Refer to Disassembled Views, Engine Component Description, and Lubrication
Description, and to the Drive Belt System Description.

All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform
approach for repairing all systems. The diagnostic flow may always be used in order to resolve a
system problem. The diagnostic flow is the place to start when repairs are necessary. For a
detailed explanation, refer to Strategy Based Diagnosis .

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the engine.

Inspect the easily accessible or visible system components for obvious damage or conditions
which could cause the symptom.

Check for the correct oil level, proper oil viscosity, and correct filter application.

Verify the exact operating conditions under which the concern exists. Note factors such as
engine RPM, ambient temperature, engine temperature, amount of engine warm-up time,
and other specifics.

Compare the engine sounds, if applicable, to a known good engine and make sure you are
not trying to correct a normal condition.

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system
is operating properly.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

symptom:

Base Engine Misfire without Internal Engine Noises

Base Engine Misfire with Abnormal Internal Lower Engine Noises

Base Engine Misfire with Abnormal Valve Train Noise

Base Engine Misfire with Coolant Consumption

Base Engine Misfire with Excessive Oil Consumption

Engine Compression Test

Engine Noise on Start-Up, but Only Lasting a Few Seconds

Upper Engine Noise, Regardless of Engine Speed

Lower Engine Noise, Regardless of Engine Speed

Engine Noise Under Load

Engine Will Not Crank - Crankshaft Will Not Rotate

Oil Pressure Diagnosis and Testing

Oil Leak Diagnosis

Drive Belt Rumbling and Vibration Diagnosis

Drive Belt Rumbling and Vibration Diagnosis

Drive Belt Falls Off and Excessive Wear Diagnosis

Drive Belt Tensioner Diagnosis

BASE ENGINE MISFIRE WITHOUT INTERNAL ENGINE NOISES

Condition

Action

Abnormalities (severe cracking, bumps or
missing areas) in the accessory drive belt.
Also worn, damaged, or misaligned accessory
drive components or excessive pulley runout.

Abnormalities in the accessory drive belt
and/or components may cause engine RPM
variations, noises similar to a faulty lower
engine and also lead to a misfire condition. A
misfire code may be present without an actual
misfire condition.

1. Inspect the accessory drive components.

2. Repair or replace all damaged

components.

Loose and/or damaged crankshaft balancer

A misfire code may be present without an
actual misfire condition.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

1. Inspect crankshaft balancer and

balancer bolt.

2. Repair or replace all damaged

components.

Loose torque converter bolts

A misfire code may be present without an
actual misfire condition.

1. Inspect torque converter bolts and

flywheel.

2. Repair or replace all damaged

components.

Loose and/or damaged flywheel

A misfire code may be present without an
actual misfire condition.

1. Inspect flywheel and flywheel attaching

bolts.

2. Repair or replace all damaged

components.

Restricted exhaust system

A severe restriction in the exhaust flow can
cause significant loss of engine performance
and may set a misfire code. Possible causes of
restrictions include collapsed or dented pipes,
plugged mufflers and/or catalytic converters.
Repair or replace all damaged components.

Air in fuel system

1. Inspect fuel filter, fuel system for leaks

and/or restrictions.

2. Repair or replace all damaged

components.

Bent and/or worn valve pushrod

1. Inspect valve pushrod and valve rocker

arm.

2. Repair or replace all damaged

components.

Sticking valve

Carbon on the valve stem or valve seat may
cause the valve to stick.

1. Inspect valves and valve guides.

2. Repair or replace all damaged

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado