Spark plugs replacement

Begin with the vehicle on level ground, engine off (cold) with the emergency brake set.

Step 1Â - Some engine's are designed with a plastic cover over the ignition coils and spark plugs.

SPARK PLUG COVER

Step 2Â - Use a socket or wrench to remove the nuts holding down the cover.

REMOVING SPARK PLUG COVER NUTS

Step 3Â - After all mounting nuts have been removed, gently remove the cover.

REMOVE SPARK PLUG COVER

Step 4Â - On COP (coil over plug) ignition system designs the spark plugs are located beneath the ignition coils.

IGNITION COILS

Step 5Â - Once the ignition coils have been uncovered, remove the coil mounting bolts. (Note: coil wiring may need disconnecting prior to this step.)

REMOVE IGNITION COIL MOUNTING BOLTS

Step 6Â - 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.)

REMOVING IGNITION COILS

Step 7Â - 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.

SPARK PLUG SOCKET

Step 8Â - Use a ratchet and extension to remove the spark plugs, ensure the socket is completely on the spark plug before removal to avoid damage.

REMOVING PARK PLUGS

Step 9Â - Once the spark plug has been removed, inspect the plug for damage and wear.

WORN SPARK PLUG

Step 10Â - 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.

NEW SPARK PLUG

Step 11Â - Before installing the new spark plugs, apply a thin layer of lubricant (anti-seize) to avoid thread galling (stripping).

APPLY LUBRICANT TO SPARK PLUG THREADS

Step 12Â - 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).

INSTALLATION READY SPARK PLUG

Step 13Â - Gently lower the spark plug down into the plug well (do not drop plug), continue installing the spark plug while threading by hand.

LOWER PLUG INTO WELL

Step 14Â - Once the spark plug have been installed by hand, use a ratchet to tighten to manufacturers specifications (snug, do not over tighten).

TIGHTEN SPARK PLUGS

Step 15Â - Next, reposition the ignition coils for re-installation.

REINSTALLING IGNITION COILS

Step 16Â - After installing the ignition coils, reinsert the mounting bolts and tighten.

TIGHTEN IGNITION COIL BOLTS

Step 17Â - Once all coil mounting bolts are tight, reinstall the ignition cover back into place.

REINSTALL SPARK PLUG COVER

Step 18Â - Install all mounting bolts and tighten, double check all steps to ensure a correct completion.

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TIGHTEN IGNITION COIL SPARK PLUG COVER

Step 19Â -Â 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.

CARBON FOULED

Step 20Â - 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.

WET SPARK PLUG

Step 21Â - Before installing a new spark plug inspect the air gap in case the plug was damaged during shipping.

MISADJUSTED AIR GAP

Step 22Â - Visually inspect the air gap and adjust to manufacturers specifications.

CORRECT AIR GAP

Step 23Â - A spark plug is constructed of a metal housing and a porcelain insulator which is very brittle and if broken or cracked will misfire so use care when handling.

Helpful Information

After replacing spark plugs the engine could stall, idle high or low, this is normal as the computer is re-learning the resistance of the ignition system which effects ignition timing. Some engine's are designed using spark plug wires which are easily removed (twist the boot to loosen seal) before removing wires. If the engine is running rich all of the spark plugs will have a black or grey soot covering the spark plug electrode and if lean all of the spark plugs will be clean and white. If one spark plug electrode appears different than the remaining spark plugs, that cylinder is having a problem. The inside of a spark plug socket is lined with a rubber cushion to safety support the spark plug insulator. Most engine's are designed with a COS system (coil over spark plug) which has no plug wires just ignition coils, other systems include HEI (high energy ignition) which utilizes a distributor and spark plug wires. If spark plug threads are damaged use a thread cleaner or tap loaded with grease to catch the metal chips that would normally go into the combustion chamber, also use a can of compressed air with the long plastic extension inserted down into the cylinder to blow out excess particles helping the removal of additional particles.

Tools and Supplies Needed

Socket set, wrench set, shop towels, protective gloves and eye wear. Carburetor cleaner set of new spark plugs.

Best Practice

Allow the engine to cool before removing spark plugs. Mark plug wires with a small piece of numbered tape to identify cylinder positions. Only install the correct spark plugs, design issues can cause internal engine damage. Remove debris from the spark plug well before removing spark plugs. Only tighten spark plugs to "snug" and install a small portion of anti-seize grease to ensure proper installation. Double check installation of spark plug wires

AC Delco Type. 41-627
This is the recommended type and part number recommended by the manufacturer.

1.02 mm (0.040 in)

And above is the recommended gap for the spark plugs.

If you have anymore questions please feel free to ask. Thank you and have a great day.

This guide will give you a step by step on how to replace the spark plugs.

https://www.2carpros.com/articles/how-to-change-spark-plugs

Please let us know what happens.

Cheers, Ken