Easy step by step guide on how to replace automotive engine spark plugs, though appearances may vary, the process is similar for most engine's.
Difficulty Scale: 4 of 10
Begin with the vehicle on level ground, engine off (cold) with the emergency brake set.
Step 1 - Some engine's are designed with a plastic cover over the ignition coils and spark plugs.
Step 2 - Use a socket or wrench to remove the nuts
holding down the cover.
Step 3 - After all mounting nuts have been removed,
gently remove the cover.
Step 4 - On COP (coil over plug) ignition system
designs the spark plugs are located beneath the ignition coils.
Step 5 - Once the ignition coils have been uncovered,
remove the coil mounting bolts. (Note: coil wiring may need disconnecting prior
to this step.)
Step 6 - Next, remove the ignition coils from the
spark plug wells and place them off to the side. (Note: Inspect ignition coil for
corrosion or signs of arcing.)
Step 7 - After the coils have been removed, use
a spark plug socket to remove the spark plugs, this socket is specially designed
to hold and protect the spark plug from damage.
Step 8 - Use a ratchet and extension to remove
the spark plugs, ensure the socket is completely on the spark plug before removal
to avoid damage.
Step 9 - Once the spark plug has been removed,
inspect the plug for damage and wear.
Step 10 - Compare the new spark plugs to the old
units to ensure a proper installation. In most cases spark plugs do not need to
be re-gaped as they are manufactured to the correct measurement for each application.
Step 11 - Before installing the new spark plugs,
apply a thin layer of lubricant (anti-seize) to avoid thread galling (stripping).
Step 12 - Insert the spark plug into the socket
while ensuring a snug fit, (the spark plug shouldn't fall out of the socket on its
own).
Step 13 - Gently lower the spark plug down into
the plug well (do not drop plug), continue installing the spark plug while threading
by hand.
Step 14 - Once the spark plug have been installed
by hand, use a ratchet to tighten to manufacturers specifications (snug, do not over
tighten).
Step 15 - Next, reposition the ignition coils for
re-installation.
Step 16 - After installing the ignition coils,
reinsert the mounting bolts and tighten.
Step 17 - Once all coil mounting bolts are tight,
reinstall the ignition cover back into place.
Step 18 - Install all mounting bolts and tighten,
double check all steps to ensure a correct completion. Step 19 - When replacing spark plugs always
check the plug condition, this inspection can detect problems inside the engine
such as rich mixture, low compression or failed injector.
Step 20 - When a spark plug is wet with oil there
is a problem with the piston rings or valve stem seals, additional problems include
plugged oil drain back holes in the cylinder head.
Step 21 - Before installing a new spark plug inspect
the air gap in case the plug was damaged during shipping.
Step 22 - Visually inspect the air gap and adjust
to manufacturers specifications.