Hundreds of engine technicians are injured or killed
each year while on the job. A majority of these incidents
resulted from broken safety rules, Figure 5-1. As an engine
technician, you will be exposed to many potentially
dangerous situations. You will be working around running
engines, engines suspended in the air on a hoist, gasoline,
and numerous other possible hazards. Moving vehicles in
the close quarters of a service facility can also be hazardous.
You must learn to control these dangerous situations and
keep your job safe and enjoyable. This chapter reviews
basic shop safety and will help you gain basic safety skills.
Types of Accidents
There are six common types of accidents—fires,
explosions, asphyxiation, chemical burns, electric shock,
and physical injuries. To create a safe working environ-
ment, you must prevent these. Each could cripple or kill
you or someone else.
Fires
A fire can cause horrible destruction, injury, and
death. Fire is the result of heat, fuel, and oxygen in the cor-
rect proportions to start combustion. When working on
engines, gasoline, diesel fuel, cleaning solvents, and oily
rags are just a few of the many possible sources of fuel in
a service facility. Fire extinguishers are rated in terms of the
type of fire for which they should be used. See Figure 5-2.
Gasoline is the most dangerous flammable in the
shop, Figure 5-3. Just a cup of ignited gasoline can engulf
a whole engine compartment in flames. The fire may then
consume the rest of the vehicle and maybe the entire shop.
A few rules for handling gasoline include:
Never use gasoline as a cleaning agent. Cleaning sol-
vents are flammable, but not as flammable as gasoline.
Keep sources of heat, such as welding and cutting
equipment, away from the engine’s fuel system.
Wipe up gasoline spills right away. Do not spread oil
absorbent (oil-dry) on a gasoline spill because the
absorbent will become flammable.
Disconnect the car battery before working on the fuel
system.
Wrap a shop towel around any fitting when discon-
necting a fuel line. This will collect fuel that leaks or
sprays out.
Store gasoline and other flammables in approved,
sealed containers.
Electrical fires can occur when a current-carrying
wire shorts to ground. This causes unlimited current flow,
which in turn causes the wire to heat up, melt its insula-
tion, and burn. See Figure 5-4. Then, other wires may short
and burn. In this repeating pattern, the wiring through
much of the car can quickly begin to burn.
To prevent electrical fires, disconnect the car battery
before working on any wiring. Since there is no power
source connected, you cannot accidentally create a short.
Explosions
An explosion is a violent expansion of gasses due to
rapid combustion. There are several possible sources of
explosion when servicing an engine or its systems. For
example, a vehicle’s battery can explode. The chemical
reaction that takes place inside of the battery to produce
electricity also generates hydrogen gas. As shown in
Figure 5-5, this highly explosive gas can surround the top
of the battery. The slightest spark or flame can ignite the
gas and cause the battery to explode. Fragments of battery
case and the battery acid can travel through the air as the
result of the explosion. Blindness, cuts, acid burns, and
scars can result.
Various other sources can result in explosions. For
example, sodium-filled engine valves, welding tanks,
propane bottles, and fuel tanks can all explode if mis-
handled. These hazards are discussed in later chapters
where appropriate.
Asphyxiation
Asphyxiation is a condition in which the body has too
little oxygen or too much carbon dioxide. It may be caused
by breathing toxic or poisonous substances in the air. Mild
cases of asphyxiation will cause dizziness, headaches, and
vomiting. Severe asphyxiation can cause death.
The most likely source of asphyxiation in a service facil-
ity is the exhaust gasses from the vehicle’s engine. Exhaust
contains very little oxygen. Coupled with the fact that the
engine is consuming oxygen for combustion, the oxygen in an
enclosed shop can quickly be depleted. In addition, an
engine’s exhaust gasses contain carbon monoxide, which is
deadly poison. Using an exhaust hose, connect the vehicle’s
tailpipe to the shop’s exhaust ventilation system, Figure 5-6.
112 Auto Engine Repair
Figure 5-1. A running engine can be dangerous. Hot parts can
cause burns. Spinning fans can cause deep cuts. Exhaust
fumes can cause asphyxiation.