DIY

Car Repair Tips: How a Home Mechanic Can Learn Home Truck Maintenance

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WILL SHELTON
Diagram: Typical positive crankcase ventilation system (PCV).

MOTHER’s Mechanic shares hints and secrets on how a home mechanic can learn home truck maintenance to keep your country car or truck in your driveway and out of the mechanic garage. (See the truck engine diagrams in the image gallery.)

Some auto components degrade with time, others with wear,
others from weather, others from poor care, and some from
combinations of the four. The condition of many has an
effect on the vehicle’s emissions, fuel economy, and
contribution to the landfill as well. If you take a little
time to learn home truck maintenance, what parts are affected by which hazard, how
to minimize the damage, and when to replace key parts
before they fail, your pocketbook–and the
environment–will benefit.

Home Study and First Steps for Home Truck Maintenance

Though it goes against the do-it-yourself inclination of
Americans, as soon as you get the new hauler home, take the
owner’s manual out of the glove box and read it through. If
you intend to work on the vehicle yourself, also obtain a
copy–current for your vehicle’s model and
year–of the Chilton, Haynes, or other all-inclusive
repair manual. They are available for under $30 at a book
or auto parts store. At the same time, get a container of
hard axle grease, several spray cans of light engine oil, a
jar of white door-hinge lube, a tube of powdered-graphite
lock lube, and a quart of good hard auto wax or one of the
new fluid non-wax car polish.

Open all the doors, pop the gas-filler-door, lift
rear-hatch covers, and see how things operate. Try
everything that moves, cinch gas cap on tight, and fasten
any loose items in the hatch area so they are stable and
rattle-free. As you go, apply hard grease to spring hinges,
white grease inside and all over door latches and over seat
slides, plus a good shot of powdered graphite into locks.
Inside such hidden spaces as the gas lid and well behind
the fender, apply a thin but thorough coating of spray-oil.
Let it drip and, in hidden crannies, let it accumulate road
dust that will help the oil skin over and hold fast. These
simple measures will stop corrosion before it can start.

The Truck Interior

Go over the inside as well. With small amounts of grease
and an oily rag, coat any hinges and metal surfaces that
won’t soil your clothing–up under the dash, inside
ash trays or metal glove box doors.

Make a note to order a set of aftermarket doorsill covers
and install them after greasing their undersurfaces as well
as the metal sill itself. In ten years, the sill will be
strong and pristine rather than rusted.

The best wear-preventative measure is to buy good-quality
floor mats and seat covers and to change them for new when
they wear.

A bed liner can protect the bottom and sides of a truck
bed. But, it can also rub, wearing off paint, hiding rust,
and voiding your warranty. Read the owner’s manual and
install only an approved liner.

Under The Truck Hood

Now, raise the hood and familiarize yourself with the
engine and accessories. Identify and check inspection ports
and dipsticks for coolant, engine oil, transmission, brake,
power-steering, windshield-washer, and any other fluids.
Read the owner’s manual as you go. You’ll note that the
engine must be off to check oil; it must be running to
check automatic transmissions. Batteries and air
conditioning contain fluids but are sealed systems.

Following our introductory illustration and your manuals,
try to locate key emissions equipment. While the engine is
still clean, remove, inspect, and re-install easily-removed
filters. Wiggle air-intake and other hoses. If anything
comes off, reattach it and tighten the compression clamp.
Inspect rubber hoses for solid attachment at both ends.

Nothing under the hood (except battery terminals and bare
metal of the underside of the hood, its hinges, and
latches) should need greasing or preserving. Oil hood
metal, and remove and coat battery terminals and the lead
cable clamps with hard grease. DO NOT wipe some
late-night-TV-hawked preparation all over your belts,
hoses, and fittings. The best of these are worthless, and
some will melt plastics and make rubber gummy.

If a fan belt squeaks, you can dress it with Ivory soap.

Underneath the Truck

A good country hauler will have ground clearance sufficient
for you to “get out and get under” as the old song says. Be
sure the emergency brake is set and wedge good stop-blocks
on the downhill side of the two uphill wheels. Lay out a
ground sheet or flattened shipping carton if the driveway
is wet or rocky and slide around beneath the machine.
Locate major drivetrain components, drain plugs, exhaust
system, and brake system parts. While you’re there, check
for leaks. If you spot any fluid on the chassis or on the
ground underneath, note its color and texture (antifreeze
is green; brake and transmission fluids, red; oils, clear
or tan), and tell the dealer. Such leaks are rare in
today’s new vehicles, but the sooner one is fixed, the
better.

Thoroughly oil-spray the undersides of the wheel wells and
all body metal you can reach. Do not coat rubber or plastic
parts (a coat of car polish can protect hard plastic).

Grease exposed (brake system) springs and spray oil over
all exposed metal surfaces of the underside of the vehicle,
painted or not. Put a ground cloth or absorbent litter
under the vehicle to catch drips.

Put a light coat of hard grease over steel drive shafts,
iron housings–but not on aluminum or other pot metal.
Spray especially well into body cavities such as the
channels under those doorsill protectors.

Put the little red plastic tube on your spray can and spray
through the drip holes at the bottom of doors and hatches
so it coats inner surfaces of the tin. Next day (and
periodically thereafter) run a wire into the drip holes to
assure that they are not clogged and will let
rust-promoting condensation and rain water flow out.
Drilling holes in the door and spraying all the
window-closing mechanisms, as is still needed on older
vehicles, is not necessary with modern corrosion-proofing
(where the entire body, door shells, and other major parts
are dipped in hot zinc galvanize and other
preservative-fluid baths). With the inside of the bottom
panel oiled occasionally, the door will last indefinitely.
(In time rubber gaskets around windows may begin to leak
and will need replacing. But that’s decades away.)

Then go over the vehicle, performing more Preventive
Maintenance (PM) chores that will save you headaches in
years to come. Locate and remove the spare. Wipe a light
coating of light oil over the wheel and liberally coat
attachment screws and nuts with hard grease so they’ll come
off easily even if not removed for the first time till ten
years hence. In storing the spare, be sure tire valve is
exposed so you can check inflation from time to time. If
the wheel is exposed to road grime beneath or on the rear,
invest in a good tire cover and install it. Put cover on
top of under-chassis tires so tar and road crud won’t
accumulate in the wheel and turn to hard-to-remove concrete
over time. Coat all sides of hold-on components with a
light coat of hard grease.

If you plan to perform major maintenance jobs yourself, go
to an auto parts store and get the largest hydraulic jack
you can afford (ten-ton), a long 3/4″-drive handle, and
sockets to fit the lug nuts that hold your wheels on. (A
compressor and air tools are even better, but expensive,
for when you have the need to do a lot of heavy work.)

Put anti-roll wedges under two wheels (as well as jack
stands; call us worrywarts, but the physical injury
possibilities here are …well…use your imagination).
Consult the manual for jack placement, and use the jack to
raise the axles so one wheel after another is just off the
ground. If you want to get under the vehicle, place large
logs or concrete (for lighter cars only, stands for heavier
models) under the frame so if the jack fails, the vehicle
will be supported by blocks.

Then remove wheels one at a time. Lightly oil insides of
wheels and grease the hub around the studs. Grease any
suspension parts you didn’t get from underneath. Don’t
lubricate the large round brake discs or other wheel/brake
parts.

Pack hard grease into threads of lugs (big screws jutting
from the end of the axle that hold wheels on) and lug nuts,
and replace wheels. See owner’s manual for tightening
sequence for lug nuts. If you have a torque wrench, tighten
to 80 lbs. (Any time you have wheels or tires serviced,
demand that lugs be tightened to no more than 80 lbs or you
may not be able to remove a flat.)

Add the 3/4 inch-drive, lug-nut-removing tools to your jack
set or carry them along with the larger jack under a seat
for much easier flat repair.

Make it a habit to check inflation of your tires (spare
included) at least once a month. Buy and use a good-quality
all-metal tire gauge, not the chronically inaccurate dials
on service station air pumps. Inflate to the precise
pressure molded into the sidewall of the tire.
Overinflation may improve gas mileage marginally but will
cause uneven wear that can ruin a tire in a fraction of its
designed (up to 80,000-mile) service life. Intentional
underinflation is OK to increase traction briefly in hard
weather. But, chronic underinflation wears tires unevenly,
too fast,–and can lose you up to 2% fuel efficiency
for each pound of pressure the tires are low. Five pounds
low means a loss of 10% of your gas money, a 10% waste of
limited petroleum resources, and 10% more needless
emissions in the air.

After pot hole time in fall and spring (in snow country),
run your hands over the surface of your front tires even if
they appear to be wearing evenly. If you feel
still-invisible sharp ridges on one side of the tread
grooves, your alignment needs checking. Fix it before wear
becomes visible, and your tires will last tens of thousands
of miles longer.

Be sure to have tires rotated and wheels balanced once or
twice a year to further even out wear. With a good tire
costing the better part of a hundred bucks these days, the
expense would be more than justified even if you weren’t
saving gas money and finite natural resources.

Backyard Truck Mechanic

Whether you do it yourself, go to a Jiffy-Lube, or to the
local mechanic, if you intend to keep a vehicle running for
twice the 100,000 miles the makers expect, change
lubricants at half the recommended intervals, and grease
all the joints for steering and suspension connections.
Better yet, buy a grease gun and hit those spots whenever
you like. Change engine oil at 3,000 miles rather than
7,500 and all running-gear lubes annually at least.

Engines are happiest running hot at hi revs. If you do a
lot of stop-and-start driving and/or travel short distances
(under ten miles) so the engine can’t heat up enough to
burn the oil clean, water and really evil corrosive agents
can build up. If the car sits for prolonged periods between
such short trips, the engine can be ruined at under 10,000
miles. Under these conditions (the hardest on an engine)
you should change oil every six months at minimum even if
it looks clear and clean.

And–under any driving regimen–spend a few bucks
more for the new synthetic lubes such as Mobil 1. These are
made from petrochemicals so you aren’t saving petroleum,
but they do retain a constant viscosity under severe
conditions. Mobil 1 resists thinning at hi temps and will
flow at – 55 degrees Fahrenheit–to say nothing of normal cold
winters when mineral oil will thicken and fail to pump up
into the engine to do its job till heated. By that time,
engine wear can be considerable. Synthetics have also been
shown to reduce engine wear, deposit less varnish, and
reduce oil consumption by eight times as compared to
mineral oils.

Always follow manufacturers’ recommendations as to
lubricant grades. But, if possible, buy the new EC grades
of oil. EC stands for Energy-Conserving. These oils contain
less phosphorous that can ruin catalytic converters. They
also increase gas mileage by .5% to 1.4%.

Keep your cooling system filled with fresh antifreeze (to
strengths on label or owner’s manual) even if you don’t
live in snow country. It contains powerful anti-corrosives
as well as freeze-proofers. If possible, have the coolant
overhauled annually at a garage, and have them backflush
the system at the same time. (If replacing your own,
dispose of the old coolant at a garage or a recycler. Don’t
just let it drain away in the grass; the stuff is toxic to
plants and animals.)

You should check the thermostat (inside a metal housing
near the hose outlet) periodically for buildup of crud.
Clean it out and (especially if the heater has been running
hot or cold) replace it every few years. See your owner’s
manuals for the thermostat temperatures recommended and
your repair manual for replacing the thermostat (get a tube
of liquid gasket to augment the paper gasket that comes
with a new thermostat).

Check hoses for cracking and leaks. Tighten clamps if they
permit. If clamps are not able to be tightened and you see
a green buildup around the hose mouth, there is a small
leak that could escalate at any time.

Inspect the cooling system hoses while you’re at it. Drain
system, remove a new hose, inspect, and reattach with a new
clamp. Replace older hoses (all of them), installing with
new clamps. Be sure to clean the outlets that hoses slip
over to remove stuck-on hose liner, corrosion, and mineral
buildup. Otherwise the hose may not fit cleanly, and leaks
will recur.

The best thing you can do to keep the cooling system clean
is to add distilled water any time the coolant level drops.
It only costs a dollar a gallon or so at any drug store.
Distilled water lacks the minerals that are found in most
water supplies and that build up as water is lost to
evaporation, clogging the narrow channels in the engine
radiator and heater core.

Most fluid changes are a routine drain and fill, but
automatic transmissions take longer and entail replacement
of the filter. Hi-tech systems may be even more involved.
ABS brake systems, for example, must be drained annually,
or old, watery fluid can ruin the sensitive electronics.
Electronic test gear and experience is required, and the
job is costly–but if you don’t have it done, a new
ABS system costs thousands of dollars.

As a rule of thumb, halve all manufacturer-specified
intervals between routine maintenance procedures, and your
car will be on the way to lasting almost forever. MOTHER
doesn’t personally guarantee this formula of course. But
auto manufacturers want their cars to last just long enough
to make you happy enough to buy another new one. Lubes
deteriorate under the heat and thrashing of use, and engine
oil carries off combustion by-products that can build up
and rust the engine from the inside out. You can’t go wrong
replacing them more often than Toyota, Honda, Ford,
Chrysler, or The General recommend.

Finishing the Outside of the Truck

Unless your owner’s manual warns otherwise (some
traditional finishes should be allowed to dry for a few
weeks), apply a good non-wax, rub-on-and-polish auto polish
such as NuFinish by ReedUnion Corp (in the orange plastic
containers). Apply to shiny paint, chrome, and other shiny
metal. Don’t put on tires, other rubber, or plastic of any
kind. Follow with a second coat in a month, and it will
last six months or longer.

A Code Reader

Today’s computerized vehicles have a reputation for mystery
that the aftermarket is finally attempting to dispel. For
some time now re-programmed chips have been available to
give selected cars added acceleration and speed. And now,
several firms are producing devices that can actually
extract repair information hidden in your vehicle’s
computer. Shops have multi-thousand-dollar consoles to get
this data, but you can buy a little handheld code-reader
for from $50 to $400. You’ll also need a good manual
describing emissions controls and engine management
systems, a book of codes, and (possibly) a special plug to
adapt the reader to your vehicle. Haynes Automotive Manuals
are one source. Any custom auto shop will be able to get
others. (They appear two years after each model
year–after warranties run out.)

When the engine acts funny or the fearsome CHECK ENGINE
light fires up, get out manual and meter, put a jump wire
or two into the computer panel, plug in the reader, punch a
button, and a sequence of lights blink, or you get an LED
reading. The code book tells you what the problem is, and
you are on your way to becoming your own service person.

Snow-Country Long-Life Specials

More than 90% of engine wear occurs on start-up. Grinding a
cold engine over and over in cold weather shortens life of
starter, battery, engine, and your temper. Have an engine
block heater installed and plug it in on cold nights. Carry
a long outdoor power cord and hook it up at work too if the
day will be cold.

Highway salt hastens rusting. It is at its worst in warmish
weather when it dissolves in slush and water, and is
splashed up to penetrate into all the crevices of your
vehicle. Wash the vehicle frequently–including an
underbody power spray. If you are buying a new vehicle,
make sure it is undercoated at the factory. If it isn’t,
there are more than a dozen aftermarket undercoating
applications you can do. Don’t live without it in cold
regions.

Almost as important is keeping the under-carriage well
oiled. After your initial work over, a professional can do
it best with a hi-powered applicator. Be sure they use new
oil (not used, toxin-laced oil). Have it applied annually
well before the start of salt-season. Reapply after every
half-dozen underbody power washes.

Major Preventive Truck Maintenance

Chase your rights under the new-car warranty so long as it
lasts. Then, to preclude serious problems, begin a program
of scheduled replacement of wearing parts. Use the dealer’s
parts store (if possible) for replacements. Major failures
cannot then be attributed to you for installing a faulty
part made of God-knows-what. Keep a log of your maintenance
as well.

But, customize the list to your vehicle and fine-tune
replacement times with your mechanic and other owners.
Between 80,000 and 120,000 miles you should have replaced
all wearing components except for the engine block and,
perhaps, the transmission, which can last for amazing time
periods if provided with good care and treatment. They
won’t last forever, however, and you may want to save up
cash. A good used engine will cost $700 to $1,200
installed; a rebuilt transmission, the same. If the vehicle
is in outstanding shape, you may want an all-new engine. It
will cost $2,500 and up; a rebuild, perhaps half that. All
other jobs will cost substantially less. Spread out over
several years, you’ll hardly notice the cost–and at
the end of the rebuild period, you’ll have virtually a new
vehicle and no monthly payments.


Not too long ago, the drivetrains of most vehicles were
laid out with a fore-and-aft engine, leading to a
transmission which led to a driveshaft that ran under the
chassis and back to a differential, powering the rear
drive wheels. On top, the engine had a carburetor and big
air-cleaner that sucked fuel down into the engine, thick
ignition wires that carried a crude ignition spark from a
mechanical distributor to spark plugs, a brake cylinder on
the fire wall, a battery and radiator up front with maybe
an air conditioner off to one side. Oil dipstick, radiator
cap, and transmission fluid checking stick or port were all
located in the same places.

In today’s downsized vehicles, the engine is liable to be
arranged sidewise over a front-wheel-drive transaxle that
combines transmission and wheel-drive in a single unit
(saving many pounds of driveshaft and gearing). The
up-jutting carburetor is gone, replaced by a featureless
black box containing a fuel injection unit capable of
better performance and greater fuel efficiency than a
“carb.” The battery is still recognizable, but the air
cleaner may be tucked over beside the wheel well. Dipsticks
and fluid-fillers may be located in unexpected spots, and
all of it is covered with a maze of wires and tubes that
can be different in each model for each year.

The Typical Layout

Follow the illustrations, and we’ll walk through the
operation of a modern engine, indicating routine
maintenance work you can perform. (Much of this work is
overlooked on modern vehicles that don’t need a
tune-up–or what remains of this once frequent
job–till they pass 100,000 miles.)

As fuel is pumped into the gas tank, air carrying
evaporated fuel is displaced–in the old days, venting
into the atmosphere and generating up to 20% of air
pollution. In modern systems, fuel is filtered out by a
charcoal canister and returned to the engine to be burned.
Like all emissions-control equipment this system cannot be
removed legally and must be maintained in operating
condition (though many are useless from neglect). It has no
adverse affect on engine performance; indeed, it decreases
fuel consumption and cost, so it pays to keep it in shape.
If the canister is dripping gasoline or is fractured, you
can replace the internal disposable filter, inoperative
purge valves, and malfunctioning or fractured housing very
easily. Parts are readily available and the manuals show
how to test the system and repair the components.

Pushed into a rubber grommet in the valve cover atop
the engine is the PCV (positive crankcase ventilation)
valve (see illustration on next page) that permits oil and
exhaust-fume-contaminated air inside the engine to be drawn
into the air cleaner housing, where it is pulled into the
cylinders to be burned and its by-products disposed of via
the exhaust system.

Here is the air cleaner housing (see illustration on
next page). It contains a disposable filter that removes
dust and bugs from engine air. If the filter element clogs
or is installed so that the gasket between housing and its
lid is not seated well all around, it will admit dust that
acts like sandpaper and can ruin an engine in short order.
At one side of the filter housing is the smaller PCV filter
that removes oil particles from the contaminated air being
drawn from the engine’s crankcase. It gets soiled and is
stained an oily brown with normal use. Don’t let it clog,
or PCV function will be in paired. Check monthly, and
change both air and crankcase-air filters any time they
appear discolored. Change the air filter as often as weekly
if your area is very dusty–if you drive often on dry,
unpaved country roads. When you change the filters, use a
cloth to clean out the inside of the air cleaner housing as
well.

The intake-air preheater is a metal tube that carries
air warmed by the exhaust manifold to the carburetor during
cold starts. This quickens both starting and warm-up by
heating incoming air so combustion is cleaner and more
efficient. The 2 inch- or 3 inch-diameter metal tubing is often
flimsy and easily dislodged. The small rubber vacuum hose
that operates a flapper valve in the air-intake can come
loose as well. An occasional check to assure that the
system is firmly in place can save you gas money and keep
the air cleaner.

There are other components of the system that you can
maintain using your manuals. Some vehicles have
bimetal-coil heat-risers at the base of the system that
will rust out in time. Wiring to the electric heaters and
electronic controls in newer systems can come loose, fray,
or break. You will never know the system is broken till the
engine won’t start and keep running on a cold morning.

The computer of a modem engine management uses
information from a dozen or more sensors to send operating
signals to actuators inside the cooling, fuel-intake, and
exhaust systems and in the engine itself. The computer
program and its operation should be automatic, seamless,
and transparent to the driver. However, sensors and
actuators are exposed to engine heat and dirt, and not all
made to last as long as they should. More problems are
caused by faulty computer input/output devices than by
serious engine malfunction–but failing to replace the
inexpensive little parts can result in serious engine
damage.

The problem that made your CHECK ENGINE light fire off
or that’s causing it to misfire, hesitate, or stall can
often be fixed by assuring that all vacuum hoses (for the
many emissions-system devices operated by exhaust suction)
and electrical fittings are firmly attached.

With a basic knowledge of the engine and experience (or
a man’s hunch or women’s intuition–often the best
diagnostic device) or with a simple hand-held code reader
and a diagnostic manual, you can often locate a faulty
sensor or activator. Even if you can’t cure the problem,
you can pinpoint the source for a mechanic, saving him
learning time and saving you repair costs.

Following are the major components of the engine
management system. Most are small and may be located
anywhere on the auto. They are interconnected by vacuum
tubing or wires–all of which must remain sound.

The computer itself can be located inside the cab under
the seats, under the dash, or (as here) on an exterior fire
wall. There isn’t much that you or I can do but make sure
it is firmly fixed in place and that all wires are firmly
attached.

MAP (manifold absolute pressure) is the vacuum caused
by air-fuel mix entering the engine. The sensor that reads
its value is connected to a hose leading into the intake
manifold; breaks in the hose are a common problem source
that you can identify and fix easily.

MAF (mass air flow) and VAF (vane air flow) sensors
gauge the air flowing into the engine. The MAF type are
all-electrical. But a VAF contains a mechanical flapper
valve that can corrode and break or become fouled. If you
have the latter, assure that it works freely. Removing the
vent and squirting with carb cleaner periodically will
prevent jams.

Air and water temp sensors are solid-state devices with
electrical wires that can work loose or break. If a code
readout indicates problems, the manual will give test
parameters. Replacement is easy (if you can find the
infernal things).

This applies as well to the oxygen sensor in the
exhaust manifold and to sensors for the EGR valve, vehicle
speed, air control valves, and more little gadgets located
all over the vehicle. You can avoid the most common
problems by getting a repair manual, locating each device,
determining how it should look when new, and checking it
periodically to replace vacuum hoses or electrical
connectors that have come loose. Or, replace it
preemptively to avoid problems.

In the future, when replacing wearing parts (installing
a rebuilt carburetor, for example), plan to replace the
attendant electronic gadgetry as well (on the carb, install
a new throttle-position sensor and any fuel or airflow
measuring devices). The manual will show how–but
won’t tell you when.

Fuel-intake systems incorporate filters with elements
that should be replaced periodically. Especially with
easilyclogged fuel-injection systems, this job should be
done by a qualified mechanic. Indeed, some manuals
recommend that the final filter never be removed and rely
on a prefilter located nearer the tank in the fuel line.
You can avoid most contaminated-fuel problems by buying
fuel from reliable brand name stations from pumps with
water separators/filters and by assuring that the nozzle
and area around the filler pipe is clean before you gas up.
If a section of rubber fuel line is accessible under the
hood, you can insert a small replaceable in-line filter as
well. Be sure to replace it periodically.

Carburetors (if your vehicle still has one) have
externally-mounted automatic chokes, base heaters, and
other devices for easy and automatic starting. Automatic
chokes are operated by suction or electricity, and the
vacuum tubes or wires can work loose. Or, the actuators
wear out in time. Indeed, the infamous “choke pull-off” is
still a common cause of hard starting. It is easily
replaced but should be done by an experienced mechanic
unless you are a dedicated auto DIY’er with a full
mechanic’s tool set. Ditto for carb adjustments (if any are
possible) as well as an eventual rebuild or
replacement.

Jets on fuel-injection systems need replacing
periodically, as do the pump and plumbing. This definitely
should be left to the pros.

Modern engines eliminate NOx, an Ozone contributor,
from emissions by injecting a small amount of low-oxygen
exhaust gas into the fresh fuel charge. The EGR
(exhaust-gas recirculation) system that does this is
all-metal, robust, and complex, and it is best left to a
pro.

The air-injection system is the reverse of the EGR
system. It doses exhaust gasses with fresh air so
pollutants will have oxygen to burn to harmless gas and
water inside the catalytic converter. Active air injection
systems do this with an alternator-sized “smog pump” running
off the engine belts. Passive EGR systems harness changes
in exhaust pressure to do the pumping. Malfunctions do
little to influence engine performance or appearance of the
exhaust, but will turn up at an exhaust-gasses test. All of
them feature hoses and simple valves that can be tested and
replaced by a pro.

Contrary to popular opinion, a smog pump takes no more
engine power than an idler pulley. The air-injection system
is often neglected (or illegally removed) in states that do
not require an annual smog test. For the atmosphere’s sake,
leave yours in place and have it tested periodically.

Under the auto, installed in front of the muffler in
the exhaust system is the catalytic converter. It heats up
to 1,600 degrees Fahrenheit and converts pollutants into harmless gasses
and water. It may be fitted with an air inlet from the smog
pump and one or more sensors. It is normally foolproof and
will last 100,000 miles. But if you have a poorly adjusted
engine (running rich), the element inside can melt and
reduce exhaust flow, severely reducing performance. An
experienced mechanic can spot a clogged converter by
feeling the vehicle’s exhaust. So can you . . .if you know
what it should be.

So, learn all you can about how the machine operates,
how it looks, feels, and smells when new. Then, you’ll be
able to diagnose many problems and fix as many as you care
to tool up for.