GM 25334145
Spark Plug

It is essential to begin the Spark Plug replacement by first turning off the Ignition Switch and then removing the ignition coils. Wait until the engine temperature sinks to safe levels before taking out spark plugs for protecting the Cylinder Head threads from harm. Use a thread chaser to clean the Spark Plug recess area before new install while also removing any debris from the threads to prevent contamination that will affect plug seating. Replace the spark plugs by using engine-specific spark plugs exclusively because plugs with different heat levels cause severe engine deterioration. A round feeler gauge should be used to check the gap of new and reconditioned spark plugs to verify their fit specifications. A thread chaser should be utilized when installing spark plugs to achieve full seating and prevent cross-threading issues that could result in overheating or thread damage. Sticky substances and paints must be avoided on fasteners because they interfere with their clamping force while only acceptable when suppliers specify their use. Correct fasteners should be installed in designated spots using matching required part numbers. Replace the spark plugs to the engine so tighten them to 18 nm (13 lb ft). After that reinstall the ignition coils.

The first step to replace spark plugs includes switching off ignition power while removing the ignition coils from the vehicle. Spark Plug replacement should start only after the engine achieves full cooldown since hot removal can damage Cylinder Head threads through plug thread seizure. Maintain the cleanliness of the Spark Plug recess by removing foreign content which leads to thread impurities that obstruct new plug seating; employ a thread cleaning tool. The engine requires spark plugs from its specifications list since using different heat levels in replacement plugs can cause severe engine damage. You should measure the gap of both new and reconditioned spark plugs using round feeler gauges before assembly because the initial gap might have changed after being handled; ensure to verify the established specifications and correct the gap accordingly. The Spark Plug should pass through the Cylinder Head with smooth motion while achieving complete sitting position by using a thread chaser for thread cleaning if necessary. A complete seat of the Spark Plug combined with proper thread alignment will stop overheating and exhaust blow-by and thread damage. Install the fasteners at their intended locations by using the correct components and resisting paint or lubricant or corrosion inhibitor application unless required specifications allow their use since these materials may alter torque forces. Tighten the spark plugs to 18 nm (13 lb ft) using the engine as the installation location before adding the ignition coils.

Checks must confirm a right Spark Plug has been installed since driveability problems can emerge from incorrect plug choices according to ignition system specifications. The selected Spark Plug must have appropriate heat range properties because lower heat can cause fouling while higher heat can result in pre-ignition and engine damage. You should check the terminal post for damage while ensuring its shape is intact and conduct stability tests by twisting and pulling it; the post should not move. Check the insulator for electrical charge movement to ground between terminal post and ground as well as inspect the Spark Plug boot for damage and the recess area of the Cylinder Head for moisture since saturated boots create arcing conditions. Pay attention to any insulator cracks which might enable improper arcing of electrical charges while verifying that the center electrode gap with the side electrode is not excessively broad since this hampers Spark Plug operation. Tightening the Spark Plug based on specifications matters because improper torque can generate operational problems but extreme torque can break the insulator. The insulator tip needs inspection for signs of tracking while the side electrode should be checked for wear or breakage simultaneously with evaluation of the center electrode's tightness or damage which produces a rattling noise. Check for electrode bridges that may result from deposits while examining platinum pads on electrodes when present together with excessive fouling conditions. The last step should involve checking the Cylinder Head Spark Plug recess area for debris since damaged or dirty threads may cause installation difficulties. Cylinder operation under normal conditions produces a brown to grayish-tan appearance with little white powder residue but carbon fouling shows itself as dry fleecy black carbon forming from excessive fuel mixture scenarios and fuel injector leakage or above-average fuel pressure or air filter obstruction or improper combustion. The combined effect of weak coils alongside worn ignition wires together with wrong Spark Plug gaps can cause fouling mainly during long periods of idling and slow speed conditions. The spark intensity suffers when deposit fouling forms because of oil, coolant or additives while producing a glaze over the electrode.