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Expert
63 Answers
- Posted on Apr 28, 2010
Re: How do you change the spark plugs on a 2003 mercury...
- Most of the 4.6 Litre engines have some form
of plastic cover, mine was held in place with two 11mm nuts at the front
and press-fit connection at the back. Remove this cover to gain access
to the spark plugs. You may need to disconnect the air hose going to the
throttle body and some additional vacuum hose connections. Mark them
with masking tape and numbers if you have any question about
re-attaching them correctly. Along each side of the intake manifold you
will see 4 round coils held in place with a 7mm bolt on each one. Remove
the 7mm bolts from each coil. Each of these coils has a connector that
will be disconnected by pinching the connector to release the catch and
pulling gently. Do not worry about marking them unless the wire harness
has been modified. The factory wire harness keeps the connectors next to
the correct coil.
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Remove each coil and plug connector by gently turning the
unit to break the rubber loose from the manifold, then pulling up on the
coil/plug connector as a unit. Do not be alarmed if the rubber boot
cover comes off, you can easily reattach it to the coil. Once the coils
and rubber boots are removed, use your compressed air source or vacuum
to remove as much debris from around the spark plugs as possible.
Warning: Wear Eye Protection when using compressed air.
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Remove the spark plugs using the 5/8" spark plug socket,
swivel, extension and ratchet. Some engine installations may require
additional extensions or swivels to get the back plugs removed. It
normally takes just an 1/8 turn to break the plugs loose and then about
4-6 full turns to fully remove the spark plugs. If the plug does not
come out with the socket, use the magnetic pickup tool to pull
the plug out. You will not be able to reach it with your fingers.
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Using the feeler gauges gap your new spark plugs to the
correct gap for your vehicle. A typical
spark plug gap for this engine is .054 inch. With the plugs gapped, fit
the rubber fuel line to the top of a spark plug and then apply a small
dab of anti-seize compound to the plug threads. Work the anti-seize into
the threads a little bit and then insert the plug into the engine. The
rubber fuel line will prevent you from cross-threading the spark plug
and you should be able to turn the plug in about 3/4 turn or more
easily. If not, remove the plug and make sure that it has not picked up
any debris in the threads. If so, clear it out and try again. Once you
have all of the plugs started, use the 5/8" socket to tighten them just
1/8 turn past their stopping point. Do not over tighten as this is the
leading cause for plug-blowout with this engine series.
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With all of the spark plugs back in, you can then proceed to
replace the coil/plug connectors. Replace the 7mm bolts for each coil
and tighten them snugly but do not over tighten. With the bolts tight,
the coil/plug connector should still rotate slightly. Reconnect the
electrical connectors for each coil by gently pushing them in place
until they click. They are indexed and will fit only in one direction.
Reconnect
the air hose to the throttle body and any vacuum lines that were
removed. Replace the plastic engine cover and fasten it in place. That's
it, your done.
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