Hummer H2. Manual - part 1695

Fig. 18: Engine Identification Location 
Courtesy of GENERAL MOTORS CORP. 

The vehicle identification number (VIN) is located on the left side rear of the engine block (1) and is typically a 
nine digit number stamped or laser-etched onto the engine at the vehicle assembly plant. 

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The first digit identifies the division.  

 

2004 Hummer H2 

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

  

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The second digit identifies the model year.  

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The third digit identifies the assembly plant.  

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The fourth through ninth digits are the last six digits of the VIN.  

DIAGNOSTIC INFORMATION AND PROCEDURES 

DIAGNOSTIC STARTING POINT - ENGINE MECHANICAL 

Begin the system diagnosis by reviewing the Disassembled Views , Engine Component Description , 
Lubrication Description , New Product Information , and Drive Belt System Description . Reviewing 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 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 System Check - Engine Controls in Engine Controls - 6.0L 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 , Lubrication Description , New Product 
Information , and 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 condition. The 
diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy 
Based Diagnosis in General Information. 

Visual/Physical Inspection 

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Inspect for aftermarket devices which could affect the operation of the Engine. Refer to Checking 
Aftermarket Accessories in Wiring Systems.  

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

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

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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.  

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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 

 

2004 Hummer H2 

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

  

properly. 

Symptom List 

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

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Base Engine Misfire without Internal Engine Noises  

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Base Engine Misfire with Abnormal Internal Lower Engine Noises  

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Base Engine Misfire with Abnormal Valve Train Noise  

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Base Engine Misfire with Coolant Consumption  

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Base Engine Misfire with Excessive Oil Consumption  

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Engine Compression Test  

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

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Upper Engine Noise, Regardless of Engine Speed  

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Lower Engine Noise, Regardless of Engine Speed  

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Engine Noise Under Load  

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Engine Will Not Crank - Crankshaft Will Not Rotate  

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Coolant in Combustion Chamber  

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Coolant in Engine Oil  

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Oil Consumption Diagnosis  

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Oil Pressure Diagnosis and Testing  

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Oil Leak Diagnosis  

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Cylinder Leakage Test  

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Drive Belt Chirping Diagnosis  

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Drive Belt Squeal Diagnosis  

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Drive Belt Whine Diagnosis  

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Drive Belt Rumbling Diagnosis  

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Drive Belt Vibration Diagnosis  

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Drive Belt Falls Off Diagnosis  

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Drive Belt Excessive Wear Diagnosis  

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Drive Belt Tensioner Diagnosis  

BASE ENGINE MISFIRE WITHOUT INTERNAL ENGINE NOISES 

Base Engine Misfire without Internal Engine Noises 

Cause

Correction

Abnormalities, such as severe cracking, bumps, or missing 
areas in the accessory drive belt 
Abnormalities in the accessory drive system and/or 
components may cause engine RPM variations and lead to a 

Replace the drive belt. Refer to Drive Belt 
Replacement - Accessory .

 

2004 Hummer H2 

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

  

misfire DTC. A misfire code may be present without an 
actual misfire condition.
Worn, damaged, or mis-aligned accessory drive components 
or excessive pulley runout - May lead to a misfire DTC. 
A misfire code may be present without an actual misfire 
condition.

Inspect the components, and repair or 
replace as required.

Loose or improperly installed engine flywheel or crankshaft 
balancer 
A misfire code may be present without an actual misfire 
condition.

Repair or replace the flywheel and/or 
balancer as required. Refer to Engine 
Flywheel Replacement or Crankshaft 
Balancer Replacement .

Restricted exhaust system 
A severe restriction in the exhaust flow can cause significant 
loss of engine performance and may set a DTC. Possible 
causes of restrictions include collapsed or dented pipes or 
plugged mufflers and/or catalytic converters.

Repair or replace as required.

Improperly installed or damaged vacuum hoses

Repair or replace as required.

Improper sealing between the intake manifold and cylinder 
heads or throttle body

Replace the intake manifold, gaskets, 
cylinder heads, and/or throttle body as 
required.

Improperly installed or damaged MAP sensor 
The sealing grommet of the MAP sensor should not be torn 
or damaged.

Repair or replace the MAP sensor as 
required.

Worn or loose rocker arms 
The rocker arm bearing end caps and/or needle bearings 
should be intact and in the proper position.

Replace the valve rocker arms as required.

Worn or bent pushrods

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Replace the pushrods.  

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Inspect the top of the pistons for 
valve contact. If the top of the piston 
shows valve contact, replace the 
piston and pin assembly.  

Stuck valves 
Carbon buildup on the valve stem can cause the valve not to 
close properly.

Repair or replace as required.

Excessively worn or mis-aligned timing chain

Replace the timing chain and sprockets as 
required.

Worn camshaft lobes

Replace the camshaft and valve lifters.

Excessive oil pressure 
A lubrication system with excessive oil pressure may lead to 
excessive valve lifter pump-up and loss of compression.

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Perform an oil pressure test. Refer to 
Oil Pressure Diagnosis and 
Testing .  

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Repair or replace the oil pump as 
required.  

Faulty cylinder head gaskets and/or cracking or other 
damage to the cylinder heads and engine block cooling 
system passages - Refer to Diagnostic Starting Point - 

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Inspect for spark plugs saturated by 
coolant. Refer to Spark Plug 
Inspection in Engine Controls - 

 

2004 Hummer H2 

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2