Hummer H2. Manual — part 70

INITIAL START-UP

Start engine and operate engine at low speed while checking for coolant, fuel and oil leaks. Stop engine.
Recheck coolant and oil level. Adjust if necessary.

CAMSHAFT

Break-in procedure is required when new or reground camshaft has been installed. Operate and maintain engine
speed between 1500-2500 RPM for approximately 30 minutes. Procedure may vary due to manufacturer's
recommendations.

PISTON RINGS

Piston rings require a break-in procedure to ensure seating of rings to cylinder walls. Serious damage may occur
to rings if correct procedures are not followed.

Extremely high piston ring temperatures are obtained during break-in process. If rings are exposed to
excessively high RPM or high cylinder pressures, ring damage can occur. Follow piston ring manufacturer's
recommended break-in procedure.

FINAL ADJUSTMENTS

Check or adjust ignition timing and dwell (if applicable). Adjust valves (if necessary). Adjust idle speed and
mixture. Retighten cylinder heads (if required). If cylinder head or block is aluminum, retighten bolts when
engine is cold. Follow the engine manufacturer's recommended break-in procedure and maintenance schedule
for new engines.

crankcase conditioner be added to engine oil. The engine should be operated
for specified amount of time to aid in lifter break-in procedure.

NOTE:

Some manufacturers require that head bolts be retightened after specified
amount of operation. This must be done to prevent head gasket failure.

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Overhaul Procedures

GENERAL INFORMATION

Engine Performance Diagnostic Routine Outline

WHERE DOES DRIVEABILITY DIAGNOSIS START?

PERFORM BASIC INSPECTION

1. Verify Customer Complaint

2. Perform Visual Inspection (See Basic Diagnostic Procedures)

3. Test Engine Sub-Systems (See Basic Diagnostic Procedures)

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Mechanical Condition (Compression)

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Ignition Output

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Fuel Delivery

4. Check Air Induction System For Leaks

5. Check & Adjust Basic Engine Settings (See On-Vehicle Adjustments)

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Ignition Timing

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Idle Speed

CHECK FOR TROUBLE CODES

1. Check for Diagnostic Trouble Codes (DTCs). (See Self-Diagnostics)

2. Repair cause of DTCs.

3. Clear PCM memory and repeat self-test.

DIAGNOSE SYMPTOM

1. If no self-diagnostics available, or no trouble codes present, identify symptom.

2. See trouble shooting procedure to identify problem. (See Trouble Shooting - No Codes)

TEST SYSTEM

1. Perform required tests. (See Systems & Component Testing)

2. Verify complaint is repaired.

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Performance Diagnostic Routine Outline

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Performance Diagnostic Routine Outline

GENERAL INFORMATION

Engine Performance Safety Precautions

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Always refer to Emission Decal in engine compartment before servicing vehicle. If manual and decal
differ, always use decal specifications.

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Do not allow or create a condition of misfire in more than one cylinder for an extended period of time.
Damage to converter may occur due to loading converter with unburned air/fuel mixture.

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Always turn ignition off and disconnect negative battery cable BEFORE disconnecting or connecting
computer or other electrical components.

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DO NOT drop or shock electrical components such as computer, airflow meter, etc.

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DO NOT use fuel system cleaning compounds that are not recommended by the manufacturer. Damage to
gaskets, diaphragm materials and catalytic converter may result.

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Before performing a compression test or cranking engine using a remote starter switch, disconnect coil
wire from distributor and secure it to a good engine ground, or disable ignition.

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Before disconnecting any fuel system component, ensure fuel system pressure is released.

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Use a shop towel to absorb any spilled fuel to prevent fire.

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DO NOT create sparks or have an open flame near battery.

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If any fuel system components such as hoses or clamps are replaced, ensure they are replaced with
components designed for fuel system use.

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Always reassemble throttle body components with new gaskets, "O" rings and seals.

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If equipped with an inertia switch, DO NOT reset switch until fuel system has been inspected for leaks.

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Wear safety goggles when drilling or grinding.

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Wear proper clothing which protects against chemicals and other hazards.

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Performance Safety Precautions

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Performance Safety Precautions

GENERAL INFORMATION

TROUBLE SHOOTING

ENGINE PERFORMANCE

TUNE-UP TROUBLE SHOOTING

Problem & Possible Cause

Action

Carbon Fouled Plugs

Clogged Air Filter

Replace Air Filter

Incorrect Idle Speed

Reset Idle Speed

Faulty Ignition Wiring

Replace Ignition Wiring

Sticky Valves/Worn Valve Seal

Check Valve Train

Fuel Injection Operation

Check Fuel Injection

Wet/Oil Fouled Plugs

Worn Rings/Pistons

Overhaul/Replace Engine

Excessive Cylinder Wear

Overhaul/Replace Engine

Plug Gap Bridged

Combustion Chamber Carbon Deposits

Clean Combustion Chamber

Blistered Electrode

Engine Overheating

Check Cooling System

Loose Spark Plugs

Clean/Torque Plugs

Over-Advanced Timing

Reset Timing

Wrong Plug Heat Range

Install Correct Plug

Melted Electrodes

Incorrect Timing

Reset Timing

Burned Valves

Replace Valves

Engine Overheating

Check Cooling System

Wrong Plug Heat Range

Install Correct Plug

Engine Won't Start

Loose Connections

Check Connections

No Power

Check Fuses/Battery

Loose/Worn Timing Belt/Chain/Gears

Check Belt/Chain/Gears

Engine Runs Rough

Leaky/Clogged Fuel Injectors

Repair Fuel Injectors

Leaky/Clogged Fuel Lines

Repair Fuel Lines

Clogged Fuel Filter

Replace Fuel Filter

Incorrect Timing

Reset Timing/Check Advance

Faulty Plugs/Wires

Replace Plugs/Wires

Uneven Compression

Overhaul/Replace Engine

1998 Chevrolet Pickup C1500

GENERAL INFORMATION TROUBLE SHOOTING

1998 Chevrolet Pickup C1500

GENERAL INFORMATION TROUBLE SHOOTING