Hummer H2. Manual — part 59

GENERAL INFORMATION

Electrostatic Discharge (ESD) Warning - Basic Information

INTRODUCTION

All Electrostatic Discharge (ESD) sensitive components contain solid state circuits (transistors, diodes,
semiconductors) that may become damaged when contacted with an electrostatic charge. The following
information applies to all ESD sensitive devices. The ESD symbol shown in Fig. Fig. 1 may be used on
schematics to indicate which components are ESD sensitive. See Fig. 1 . Although different manufactures may
display different symbols to represent ESD sensitive devices, the handling and measuring precautions and
procedures are the same.

Fig. 1: Sample ESD Symbol

NOTE:

This article is intended for general information purposes only.

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Electrostatic Discharge (ESD) Warning - Basic Information

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Electrostatic Discharge (ESD) Warning - Basic Information

HANDLING STATIC-SENSITIVE CIRCUITS/DEVICES

When handling an electronic part that is ESD sensitive, the technician should follow these guidelines to reduce
any possible electrostatic charge build-up on the technician's body and the electronic part.

1. Always touch a known good ground source before handling the part. This should be repeated while

handling the part and more frequently after sitting down from a standing position, sliding across the seat
or walking a distance.

2. Avoid touching electrical terminals of the part, unless instructed by a diagnostic procedure.

3. DO NOT open the package of a new part until it is time to install the part.

4. Before removing the part from its package, ground the package to a known good ground source.

CHECKING STATIC-SENSITIVE CIRCUITS/DEVICES

1. Solid State circuits in electronic devices are shown greatly simplified in schematics. See Fig. 2 . Due to

the simplification of the electronic devices on the schematic, resistance measurements could be
misleading or could lead to an electrostatic discharge. Always follow the recommended diagnostic
procedure.

Fig. 2: Sample Schematic Showing Typical ESD Sensitive Device

2. Only measure resistance at the terminals of the devices when instructed by the recommended diagnostic

procedure.

3. When using a voltmeter, be sure to connect the ground lead first.

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Electrostatic Discharge (ESD) Warning - Basic Information

GENERAL INFORMATION

Engine Overhaul Procedures

* PLEASE READ THIS FIRST *

Examples used in this article are general in nature and do not necessarily relate to a specific engine or system.
Illustrations and procedures have been chosen to guide mechanic through engine overhaul process. Descriptions
of processes of cleaning, inspection, assembly and machine shop practice are included.

Always refer to appropriate engine overhaul article in the ENGINES section for complete overhaul procedures
and specifications for the vehicle being repaired.

DESCRIPTION

Examples used in this article are general in nature and do not necessarily relate to a specific engine or system.
Illustrations and procedures have been chosen to guide mechanic through engine overhaul process. Descriptions
of cleaning, inspection, and assembly processes are included.

ENGINE IDENTIFICATION

Engine may be identified from Vehicle Identification Number (VIN) stamped on a metal tab. Metal tab may be
located in different locations depending on manufacturer. Engine identification number or serial number is
located on cylinder block. Location varies with each manufacturer.

INSPECTION PROCEDURES

Engine components must be inspected to meet manufacturer's specifications and tolerances during overhaul.
Proper dimensions and tolerances must be met to obtain proper performance and maximum engine life.

Micrometers, depth gauges and dial indicator are used for checking tolerances during engine overhaul.
Magnaflux, Magnaglo, dye-check, ultrasonic and x-ray inspection procedures are used for parts inspection.

MAGNETIC PARTICLE INSPECTION

Magnaflux & Magnaglo

Magnaflux is an inspection technique used to locate material flaws and stress cracks. Component is subjected to
a strong magnetic field. Entire component or a localized area can be magnetized. Component is coated with
either a wet or dry material that contains fine magnetic particles.

Cracks which are outlined by the particles cause an interruption of magnetic field. Dry powder method of
Magnaflux can be used in normal lighting and crack appears as a bright line.

Fluorescent liquid is used along with a Black light in the Magnaglo Magnaflux system. Darkened room is
required for this procedure. The crack will appear as a glowing line. Complete demagnetizing of component

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Overhaul Procedures

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Overhaul Procedures

upon completion is required on both procedures. Magnetic particle inspection applies to ferrous materials only.

PENETRANT INSPECTION

Zyglo

The Zyglo process coats material with a fluorescent dye penetrant. Component is often warmed to expand
cracks that will be penetrated by the dye. Using darkened room and Black light, component is inspected for
cracks. Crack will glow brightly.

Developing solution is often used to enhance results. Parts made of any material, such as aluminum cylinder
heads or plastics, may be tested using this process.

Dye Check

Penetrating dye is sprayed on the previously cleaned component. Dye is left on component for 5-45 minutes,
depending upon material density. Component is then wiped clean and sprayed with a developing solution.
Surface cracks will show up as a bright line.

ULTRASONIC INSPECTION

If an expensive part is suspected of internal cracking, ultrasonic testing is used. Sound waves are used for
component inspection.

X-RAY INSPECTION

This form of inspection is used on highly stressed components. X-ray inspection may be used to detect internal
and external flaws in any material.

PRESSURE TESTING

Cylinder heads can be tested for cracks using a pressure tester. Pressure testing is performed by plugging all but
one of the holes of cylinder head and injecting air or water into the open passage.

Leaks are indicated by the appearance of wet or damp areas when using water. When air is used, it is necessary
to spray the head surface with a soap solution. Bubbles will indicate a leak. Cylinder head may also be
submerged in water heated to specified temperature to check for cracks created during heat expansion.

CLEANING PROCEDURES

All components of an engine do not have the same cleaning requirements. Physical methods include bead
blasting and manual removal. Chemical methods include solvent blast, solvent tank, hot tank, cold tank and
steam cleaning of components.

BEAD BLASTING

1998 Chevrolet Pickup C1500

GENERAL INFORMATION Engine Overhaul Procedures