Working on your car can be dangerous.
This page shows just some of the potential
risks and hazards, with the aim of creating a
• Don’t remove the radiator or expansion
tank cap while the engine is hot.
• Engine oil, automatic transmission fluid or
power steering fluid may also be dangerously
hot if the engine has recently been running.
• Beware of burns from the exhaust system
and from any part of the engine. Brake discs
and drums can also be extremely hot
immediately after use.
• When working under or near
a raised vehicle,
jack with axle
stands, or use
under a car which
is only supported by a jack.
• Take care if loosening or tightening hightorque nuts when the vehicle is on stands.
Initial loosening and final tightening should
be done with the wheels on the ground.
• Fuel is highly flammable; fuel vapour is
• Don’t let fuel spill onto a hot engine.
• Do not smoke or allow naked lights
(including pilot lights) anywhere near a
vehicle being worked on. Also beware of
(electrically or by use of tools).
• Fuel vapour is heavier than air, so don’t
work on the fuel system with the vehicle over
an inspection pit.
• Another cause of fire is an electrical
overload or short-circuit. Take care when
repairing or modifying the vehicle wiring.
• Keep a fire extinguisher handy, of a type
suitable for use on fuel and electrical fires.
• Ignition HT
voltage can be
people with heart
problems or a
work on or near the
ignition system with
the engine running or
the ignition switched on.
• Mains voltage is also dangerous. Make
sure that any mains-operated equipment is
correctly earthed. Mains power points should
be protected by a residual current device
(RCD) circuit breaker.
Fume or gas intoxication
• Exhaust fumes are
poisonous; they often
monoxide, which is
rapidly fatal if inhaled.
Never run the
engine in a
such as a garage
with the doors shut.
• Fuel vapour is also
poisonous, as are the vapours from some
cleaning solvents and paint thinners.
Poisonous or irritant substances
• Avoid skin contact with battery acid and
with any fuel, fluid or lubricant, especially
antifreeze, brake hydraulic fluid and Diesel
fuel. Don’t syphon them by mouth. If such a
substance is swallowed or gets into the eyes,
seek medical advice.
• Prolonged contact with used engine oil can
cause skin cancer. Wear gloves or use a
barrier cream if necessary. Change out of oilsoaked clothes and do not keep oily rags in
• Air conditioning refrigerant forms a
poisonous gas if exposed to a naked flame
(including a cigarette). It can also cause skin
burns on contact.
• Asbestos dust can cause cancer if inhaled
or swallowed. Asbestos may be found in
gaskets and in brake and clutch linings.
When dealing with such components it is
safest to assume that they contain asbestos.
• This extremely corrosive acid is formed
when certain types of synthetic rubber, found
in some O-rings, oil seals, fuel hoses etc, are
exposed to temperatures above 4000C. The
rubber changes into a charred or sticky
substance containing the acid. Once formed,
the acid remains dangerous for years. If it
gets onto the skin, it may be necessary to
amputate the limb concerned.
• When dealing with a vehicle which has
suffered a fire, or with components salvaged
from such a vehicle, wear protective gloves
and discard them after use.
• Batteries contain sulphuric acid, which
attacks clothing, eyes and skin. Take care
when topping-up or carrying the battery.
• The hydrogen gas given off by the battery
is highly explosive. Never cause a spark or
allow a naked light nearby. Be careful when
connecting and disconnecting battery
chargers or jump leads.
• Air bags can cause injury if they go off
accidentally. Take care when removing the
steering wheel and/or facia. Special storage
instructions may apply.
Diesel injection equipment
• Diesel injection pumps supply fuel at very
high pressure. Take care when working on
the fuel injectors and fuel pipes.
Warning: Never expose the hands,
face or any other part of the body
to injector spray; the fuel can
penetrate the skin with potentially fatal
• Do use eye protection when using power
tools, and when working under the vehicle.
• Do wear gloves or use barrier cream to
protect your hands when necessary.
• Do get someone to check periodically
that all is well when working alone on the
• Do keep loose clothing and long hair well
out of the way of moving mechanical parts.
• Do remove rings, wristwatch etc, before
working on the vehicle – especially the
• Do ensure that any lifting or jacking
equipment has a safe working load rating
adequate for the job.
A few tips
• Don’t attempt to lift a heavy component
which may be beyond your capability – get
• Don’t rush to finish a job, or take
unverified short cuts.
• Don’t use ill-fitting tools which may slip
and cause injury.
• Don’t leave tools or parts lying around
where someone can trip over them. Mop
up oil and fuel spills at once.
• Don’t allow children or pets to play in or
near a vehicle being worked on.