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Do spark plug wires wear out?
You bet. That's because spark
plug wires aren't actually
made of wire. They're made of delicate
carbon fibers. Over time, the carbon
breaks down and the fibers separate, causing
high electrical resistance. High resistance
degrades the spark, resulting in poor
combustion, misfires, lousy gas mileage and ultimately a glowing "Check Engine"
light. If you let that condition go on too
long, the wires can start to leak voltage to
nearby engine parts, causing arcing, severe
performance problems, and even ignition
component failures.
That's why it pays to replace your spark
plug wires before they wear out. We recommend
changing them during spark plug changes (whenever your owner's
manual recommends, or between 60,000
and 100,000 miles). Here, we'll show you
which materials and tools you'll need and
all the steps required to do a quality job of
your own. You'll save about $80 on shop
labor charges and ensure that you won't
be in for the costly diagnostic fees associated
with worn spark plug wires. The whole job is pretty easy and will only take
about an hour.
Before you start the job, use a digital
camera to record how the wires attach to
the coil/distributor/coil pack and the path
they take to each plug. Notice how each
wire wraps around the others and how
they are arranged in the plastic retaining
clips. They're arranged that way for a reason:
to prevent cross-firing and interference
with other engine sensors. So be sure
to put them back in the same manner.
1. Use your digital camera to record
the route of each wire. They have to
go back the same way.
When you're at the auto parts store, we
recommend that you buy a premium set
of wires. The economy wire set we looked
at didn't match the factory connectors,
and the individual wires were either too
long or too short for our vehicle. The premium
set carried a lifetime warranty; the
economy set, only two years. Next, invest
in a spark plug wire puller tool (Photo 3).
A wire puller tool makes removal much
easier and saves a lot of busted knuckles.
To use it, simply grasp the boot with the
rounded jaws, rotate left and right, then
pull straight out. This is a tool that's worth
the investment.
Some manufacturers precoat the
insides of the plug and coil/distributor
boots with dielectric silicone grease. The
grease prevents the boots from sticking to
the plug or coil/distributor. It also provides
an additional layer of insulation to
prevent voltage from traveling down the
inside of the boot. If your set isn't precoated,
purchase a small tube of silicone
grease and run a bead around the inside of
each boot.
Then remove one old wire at a time and
match it to a replacement wire of the same
length. Route the new wire and push the
boot onto the plug or coil/distributor
until you feel it click. Repeat the procedure
for each wire.
2. Uncoil the new spark plug wires and
sort them by length.
3. Using a wire puller, twist the boot to
break the seal from the plug and
then pull off the old plug. Match the old
wire length to the new wire.
4. Apply dielectric grease to both the
plug and the coil/distributor end of
each wire. Route the wire and press it
onto the plug/coil tower until it clicks.
Wire Puller
Lisle 51750
Adjustable
Spark Plug
Wire Puller,
$22.95.
Dielectric
grease
Dielectric
grease is
available
at any
auto
parts
store.
Wire options
The premium
replacement
exactly
matches the
factory connectors.
The
economy wire
doesn't.
Buyer's Guide
Lisle tools are available at www.toolsource.com
and at CARQUEST Auto Parts stores nationwide.
