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For
maximum fuel economy and peak engine performance,
your spark plugs should be replaced every 2 years
or 30,000 miles.
How to Change Your Spark Plugs
What you will need:
- 3/8 drive Spark plug socket, extension and
ratchet
- New set of spark plugs
- Spark plug gaping gauge
- Rag or brush
- Length of 5/16" vacuum line about 12"
long
Why replace your spark plugs?
Spark plugs are one of the most important parts
of your vehicle's engine. Your spark plugs should
be replaced every 2 years or 30,000 miles to maintain
maximum fuel economy and peak engine performance.
This may vary depending on the make and model
of your vehicle. Some models will go as far as
100,000 miles before the plugs need replacement.
Replacing your spark plugs isn't that difficult
but, be sure to read all the instructions listed
below.
Before you start:
Get all the tools you'll need and gap your spark
plugs.
The proper spark plug gap can be found on the
engine specifications decal under the hood. Get
the right plugs for your car. I always recommend
using the brand of plugs originally installed
in your car from the factory. For Ford products
they are Motorcraft , General Motors products
use AC Delco and in Chrysler products they are
Champion. In Japanese cars I would use NGK and
in German cars I would use Bosch. Consult a parts
guide to get the correct spark plugs. A cross
reference will not often get you the exact plug
you need.
Okay, let's get to work.
- Always change your spark plugs with the engine
cold. Grabbing the plug wire by the boot, carefully
pull the spark plug wire from the end of the
spark plug. Do not pull the wire itself. If
the boot sticks, twist the boot left and right
and pull the plug wire off. I would recommend
changing the plugs one at a time to avoid mixing
up the spark plug wires.
- If you have it, use compressed air to blow
any dirt away from the spark plug area. Otherwise,
clean off the old plug and the area around it
with a rag or small brush. This will help prevent
any foreign material from falling into the cylinder
when the plug is removed.
- Remove the plug by turning it counterclockwise
with a spark plug socket and ratchet. Once you
crack it loose, spin it out about three or four
turns. Then remove the socket and remove it
completely by hand. If you can't reach it, slip
the 5/16" vacuum line over the spark plug
and turn it out with that.
- If you haven't done so yet, gap the new plug
with a spark plug gap gauge (The proper gap
can be found on the engine specifications decal
under the hood). Slip the correct thickness
wire or feeler between the inner and outer electrodes
at the tip of the plug. A flat gauge is good;
the wire type is better. When the plugs are
properly gapped, the wire or feeler should slide
between the electrodes with a slight drag. If
the gap is incorrect, gently bend the outer
electrode slightly until the correct gap is
achieved. Make sure that the outer electrode
is centered directly over the inner electrode.
If it's not, align the two by gently bending
the outer electrode
- Take a good look at the cylinder head threads.
They should be in good condition, clean, and
free of dirt and debris. This new spark plug
should freely screw into the cylinder head by
hand. Any binding of the plug is an indication
that there's a problem. Remove the plug and
inspect the threads.
- Insert the plug into the spark plug hole
by hand and turn it clockwise until it's snug.
I always attach a short piece of 5/16"
rubber hose to the top of the plug and use it
as an extension to install the new plugs
- After installing the plug by hand as far
as it will go, firmly tighten it with a spark
plug wrench or socket. It's a good idea to use
a torque wrench, if one is available, to ensure
that the plug's properly seated. Be very careful;
do not over tighten the spark plugs. Remember,
you'll get an accurate torque reading only if
the spark plug and cylinder head threads are
clean and dry.
- Reattach the plug wire to the new plug. Use
a twisting motion on the boot until it's firmly
seated on the top of the plug. You will feel
and hear a click as the wire clamps onto the
spark plug.
Repeat these same steps for the other plugs.
If you take your time this is a fairly easy job
and will probably take you about an hour, depending
on how many plugs your vehicle has.
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