GM 12681665
Spark Plug

The Spark Plug replacement process should begin with turning off the ignition before removing the Ignition Coil. Prior to removing the Spark Plug you must clean its recess area to stop external substances from entering the Cylinder Head space and creating possible engine framework failure and thread contamination. A thread chaser tools should be used to clean all contamination from the threaded areas. Before proceeding with Spark Plug removal operate compressed air through the Spark Plug cavity until the engine reaches normal temperature because removing plugs from a hot engine might result in thread restricting. Dismantle the Spark Plug after obtaining readiness status. Install only the spark plugs that match the vehicle's specifications precisely because wrong plug types create severe damage to the engine components. A round feeler gauge must be used to check the gap of new and reconditioned spark plugs until it reaches the specified Spark Plug gap. Look for easy thread insertion and complete seat placement of the Spark Plug into the Cylinder Head by using a thread chaser when needed to prevent damage from cross-threading or poor seating which could result in overheating or damaged threads. Fit the Spark Plug before torquing it to 20 n.m (15 lb ft) and reinstall the Ignition Coil.

You should start by taking off the Spark Plug Wires before turning each Spark Plug 1 or 2 complete revolutions. First wipe away dirt from the spark plugs by brushing or using compressed air before you remove spark plugs singly into numbered trays. Check each Spark Plug washer fits correctly before testing the gap width and adjusting it when needed to reach 1.524 mm (0.060 in). Begin each plug hand-tightening process at specific torque levels that include 15 n.m (11 lb ft) for used heads and 20 n.m (15 lb ft) for new aluminum heads and 30 n.m (22 lb ft) for new iron heads. Reinstall the Spark Plug Wires at the completion of the procedure.

Before starting the replacement of spark plugs you should switch off the ignition and then detach the ignition coils. Let the engine cool down first before you take out the spark plugs because this prevents seizing of Cylinder Head threads. Start by cleaning the Spark Plug recess to stop dirt from entering the Cylinder Head because it would contaminate the threads to prevent a correct fit of new plugs; use a thread chaser to clear any present contamination. New plugs require their Spark Plug gap measurement which must be compared against the specifications while necessary adjustments should be made before installing only sanctioned plugs since improper plug temperatures can destroy the engine. A round feeler gage must assess the gap of both new and reconditioned spark plugs before installation since handling might alter the measured gaps from their pre-set values. Use the provided thread chaser to insert the spark plugs into the Cylinder Head until complete seating occurs; avoid cross-threading by checking for seamless thread fit and do not tighten beyond 18 n.m (13 lb ft) torque specifications without using a thread chaser. Follow sequence by tightening Ignition Coil spark plugs up to 18 n.m (13 lb ft). Then reinstall all ignition coils.

The essential equipment for Spark Plug replacement includes the Spark Plug centering sleeve (J 42068) among other tools. Begin the task by removing ignition coils and protect your eyes with safety glasses for avoiding dirt particles. Using low-pressure air clean the Spark Plug recess area to stop dirt or foreign material entry into the Cylinder Head because this could harm the engine or contaminate Cylinder Head threads thus the new plugs may not fit properly. A thread chaser must be used to eliminate any pollutants from the thread area. Secure the Spark Plug centering sleeve (J 42068) onto a 3/4 extension to shield the Spark Plug socket from possible damage that would crack the insulator of the plug. Warming up the engine first is essential else the plug threads may freeze up and become damaged. Look for signs of damage on the removed spark plugs then use a round feeler gauge to verify all new and reconditioned spark plugs have correct gaps since personnel handling can alter them. Operators should install factory-specified spark plugs on their vehicles since engine damage occurs when non-matching plugs of different temperature levels are used. A thread chaser helps secure complete plug seating into the Cylinder Head while preventing cross-threading or overheating and thread damage so take appropriate measures if necessary. Fit the spark plugs into the cylinder heads before tightening them to 25 n.m (18 lb ft) then install all ignition coils.

Start by removing the Spark Plug wire through a 1/2 twist of the boot before pulling just at the boot. Before removing the Spark Plug, users should clean its surroundings using either a brush or compressed air. Each additional Spark Plug should get placed in a designated tray which indicates the cylinder it belongs to. Position the Spark Plug washer correctly while inspecting the gap between the Spark Plug and checking it for necessary adjustments. Insert the Spark Plug in the right cylinder before tightening it to 15 n.m (11 lb ft). When installing the Spark Plug wire you must push sideways on each boot to inspect proper seat before putting back any loose boot.

Refer to ignition system specifications to obtain proper Spark Plug information before confirming installation because a mismatched Spark Plug might damage the driveability performance. It is important to verify that the Spark Plug heat range matches the correct specifications because both incorrect temperature settings can cause fouling or pre-ignition conditions leading to engine damage. Check the terminal post for all signs of damage while making sure it stays fixed in place by twisting and pulling. Also inspect for any potential bending or breaking of the post. Check the insulator for electric charge path abnormalities that result from terminal post-to-ground electrical connections and examine both the Spark Plug boot and Cylinder Head recess area to detect moisture which can lead to arcing. Examine the insulator region for open areas which potentially enable electrical charge arcing instead of electrode contact (3, 4). The operational efficiency of the Spark Plug is determined by the correct measurement of the center electrode-side electrode distance and correct torque adjustment based on ignition system specifications to prevent operation issues. The insulator tip must be checked for tracking indications while side electrode wear and breakage and center electrode looseness and damage are assessed through a rattling sound. Check for electrode bridges (3, 4) because of accumulated deposits and examine platinum pads on electrodes (3, 4) for wear symptoms when such pads exist and assess excessive fouling amounts. Ending the examination by checking the Cylinder Head Spark Plug recess area for debris since damaged threads or contaminants can lock the plug in place during installation. The correct color of normal operation is brown to greyish-tan and indicates small white powdery deposits, but carbon fouling shows up as dry black flaky carbon which stems from rich fuel mixtures, leaking fuel injectors, excessive fuel pressure and restricted air filters and incorrect combustion conditions. Additional carbon fouling sources include weak ignition coils alongside broken ignition wires and improper Spark Plug gaps and prolonged engine idling and driving periods under low power demands. The spark intensity decreases when deposits resulting from oil or coolant or particular additives form glaze on electrodes.

Start by detaching the Spark Plug wire then turning the Spark Plug 1 or 2 warehouse revolutions before removal. A brush or compressed air tool should clean the area surrounding the Spark Plug before its removal. Each plug being removed should go in a labeled tray used for its corresponding cylinder. Position the Spark Plug washer correctly before checking the Spark Plug gap and adjusting it to 1.524 mm (0.060 in) when necessary for installation. The Spark Plug installation requires hand starting the plug in its designated cylinder followed by screw tightening it to a torque size of 20 n.m (15 lb ft) on used heads and 30 n.m (22 lb ft) on new heads. Read the instruction to install the Spark Plug wire.

Thoroughly check the terminal post to confirm its structural integrity as well as the tightness of its connection by twisting and pulling it because the terminal should not move. An inspector should check the insulator to detect flashover along with carbon tracking and soot formation that occurs through electrical charge paths from the terminal post to ground. Check for boot damage while inspecting the Spark Plug recess area whether it has moisture from oil, coolant or water since waterlogged boots can lead to ground arcing. Check the insulator for any present cracks that can cause electrical charge to short circuit instead of traveling through the electrodes (3, 4). A poor arcing condition requires assessment along with a measurement of the gap space between the center electrode and side electrode terminals to prevent Spark Plug malfunction. The wrong Spark Plug torque choice will cause operational issues but applying too much torque can break the insulator . The technical specialist must inspect the insulator tip region for tracking instead of the center electrode area while testing if side electrode and center electrode are intact through Spark Plug shaking; rattling sounds indicate internal breakdown and loose center electrodes lead to reduced spark energy. A detailed inspection must check whether electrode (3, 4) associations exist and examine the condition of platinum pads on electrodes (3, 4) where present. Observe the recess area on the Cylinder Head for debris since damaged threads or debris can stop the Spark Plug from installing correctly.

The first thing to do when changing spark plugs is to pull off the Spark Plug Wires and unscrew the plugs a little. Clear away dirt from the spark plugs with either a brush or compressed air, then take out each Spark Plug one by one and put it into a tray with its cylinder number written on it. As you put in the spark plugs, confirm the washers are set right and use a gauge to adjust the gap until it's 1.524 mm/0.060 in. Place the spark plugs in their right cylinders, then fasten them with the proper force shown here: for used heads, tighten to 15 n.m (11 lb ft); if the heads are used, tighten them to 15 n.m (11 lb ft); tighten new aluminum heads to 20 n.m (15 lb ft), and new iron heads to 30 n.m (22 lb ft). Make sure to put the Spark Plug Wires back into their places.

The first step to remove the Spark Plug wire entails twisting the boot a 1/2 turn followed by boot pull only from its base. First wipe away all dirt surrounding the Spark Plug by employing a brush and compressed air before you detach the Spark Plug. Multiple plugs being replaced should be sorted into different trays which include labels for their specific cylinder numbers. Install the Spark Plug washer correctly before checking the plug gap according to ignition system specifications for any adjustments. The mechanic must start and tighten the Spark Plug by hand in each cylinder to 15 nm (11 lb ft) follow the fastener safety precautions which protects vehicle integrity. Examine the Spark Plug wire after installation through minor side pushing motion on each boot to verify its seating before reattaching loose boots when necessary.

Use a round feeler gauge to ensure accuracy, as pre-set gaps may change during handling; the spark plug gap must match the spark plug gap specification.

Verify that the correct spark plug is installed, as an incorrect spark plug can lead to driveability issues.

Use compressed air to clear debris, ensuring to clean the spark plug recess area beforehand.

Ensure each spark plug washer is properly positioned and inspect the spark plug gap, adjusting as necessary to meet the specification of 1.524 mm (0.060 in.).

Correctly position the spark plug washer and inspect the spark plug gap, adjusting it as needed to 1.016 mm (0.040 in).

Remove the plugs one at a time, placing each in a tray marked with the corresponding cylinder numbers.

An incorrect spark plug can lead to driveability issues.

Verify that the correct spark plug is installed, as an incorrect spark plug can lead to driveability issues.

Reinstall the spark plug wires and the fuel rail covers.

Hand start the spark plugs in their respective cylinders, ensuring to tighten them appropriately.

Loosen each spark plug by 1 or 2 turns.

Remove the air cleaner outlet duct and the intake manifold cover if necessary.

Place each in a tray marked with the corresponding cylinder number.

Apply dielectric grease GM PN 12345579 (Canadian PN 10953481) or equivalent to the inside of the spark plug wire boots before installing the appropriate spark plug wire boot(s) back onto the spark plug.

Twist the boot 1/2 turn and pull only on the boot or use a tool designed for this purpose.

Clean any dirt around the spark plugs using a brush or air blast.

Inspect the spark plug gap and adjust as necessary to meet the specification of 1.524 mm (0.060 in).

Ensure each spark plug washer is properly positioned and inspect the spark plug gap, adjusting as necessary to meet the specification of 1.524 mm (0.060 in).

Loosen each spark plug one or two turns.