GM 97226202
Glow Plug

Driveability problems may occur when the wrong Spark Plug exists in the system so verify that the proper plug is in place. Use a Spark Plug with an appropriate heat range to prevent damage to both the engine and Spark Plug which might occur with either a cold plug causing fouling or hot plug triggering pre-ignition. The terminal p05 must be checked for damage by inspecting the terminal post for bends or breaks. Additionally, the post should stay stationary when twisting or pulling the terminal. Check the insulator for both sparkover and carbon track issues caused by electric charge travel from terminal post to ground while inspecting the Spark Plug boot and Spark Plug recess area in the Cylinder Head for liquid moisture as boot saturation leads to arcing problems. The proper operational condition of the insulator can be checked by examining it for potential electrical charge-allowing cracks that may produce arcing instead of reaching the electrodes (3, 4). Additionally test for possible arcing issues by verifying that the center electrode and side electrode terminal gap matches ignition system specifications to prevent impediments to Spark Plug functioning. According to ignition system specifications, adequate torque must be confirmed when installing spark plugs because improper torque can lead to operational deficits and excessive torque may cause the insulator to break. Check for tracking along the insulator tip instead of the center electrode section and verify the condition of side electrode and center electrode through a motion test; hear a rattling sound means internal damage exists while loose center electrode produces weak sparks. Inspection of electrodes (3, 4) must confirm they have no deposits between them while checking for worn off or missing platinum pads on the electrodes (3, 4) and verifying decreased fouling. Check the Cylinder Head Spark Plug recess to examine for debris since poor thread condition can impede full seating when installing the Spark Plug. A normal Spark Plug will exhibit brown to grayish-tan coloring with limited white powdery residue but carbon fouling will show itself as dry black carbon soot that stems from conditions like rich fuel mixtures, fuel injector leakage, high fuel pressure, obstructed air filters, incorrect combustion, reduced ignition output, weak coils, worn ignition wires, or misaligned Spark Plug gap. Slowing down the engine during light loads at idle periods prevents combustion deposits from burning fully off resulting in spark intensity loss together with deposit fouling caused by oil or coolant or some additives. However, solid powdery deposits normally do not alter spark intensity unless they create a coating on the electrode.

Use the correct Spark Plug to prevent driveability problems but verify the heat range to stop both plug fouling caused by cold plugs and engine damage due to hot plugs. Examine the terminal post for damage before testing its stability by twisting the terminal. Check for no irregular bending and complete solidity of the post. The insulator should be checked for flashover and carbon tracking while the Spark Plug boot needs examination for damage and the Cylinder Head recess area must be free of moisture since wetness can lead to arcing. Research the insulator for potential cracks that enable electrical charge to arc apart from the electrodes (3, 4). Also check that the center electrode gap to side electrode gap matches specified dimensions to ensure proper operating conditions. Suitable Spark Plug torque should be verified because incorrect torque levels generate operational problems but excessive torque may break the insulator. A visual examination of the insulator tip needs to be done to check for tracking while evaluating the side electrode for wear or breakage together with center electrode assessment for damage or looseness based on a rattling sound. Transparent electrode gaps must be examined for bridged electrodes that result from deposit accumulation while worn or missing platinum pads require inspection along with high levels of fouling on electrodes (3, 4). The inspection of the Cylinder Head's Spark Plug recess area should be completed for checking whether debris or damaged or dirty threads exist which might impact the installation quality. The Spark Plug operates normally with brown to grayish-tan coloration and white powdery dust but carbon fouling presents itself as dry black carbon soot stemming from rich fuel mixtures or leaking fuel injectors or excessive fuel pressure or restricted air filters or improper combustion or diminished ignition system voltage or weak coils or broken ignition wires or improper Spark Plug gap. The operation at low speed or persistent idling will stop the normal burning of combustion deposits and deposit fouling from oil, coolant and additives can minimize spark intensity by forming electrode glaze.

Use the proper Spark Plug type and pick one with a heat range that fits the engine needs to block Spark Plug fouling by a mismatched temperature setting and pre-ignition issues from an improper heat range selection. Check the terminal post for damage while verifying that it does not bend as well as checking for looseness by twisting and pulling; the post must stay in position. Check if electrical charge passes between terminal post and ground causing flashover or carbon tracking problems on the insulator while investigating if Spark Plug boot damages exist along with moisture in the Cylinder Head recess the boot rests inside. Check for cracks in the insulator that may cause electrical charge to bypass the electrodes (3, 4). Also verify the center electrode distance to side electrode to match specified requirements since large gaps affect appliance performance. Operational malfunction might occur from improper Spark Plug torque adjustment since inadequate torque can harm the device but excessive torque might make the insulator break. Check for insulator tip tracking while examining the side electrode for damage as well as breakage and center electrode for loose or damaged components through a rattling sound. Check whether there are any electrode bridges (3,4) caused by deposits and examine platinum pads on electrodes (3,4) if present. Excessive patient fouling requires attention when preparing the Spark Plug seat because thread disorders may block the proper installation of the assembly. Typical operational color ranges from brown to grayish-tan with minimal white deposits yet carbon fouling takes form as light black dry carbon sediment caused by fuel mixture overabundance or fuel injector leakage or elevated fuel pressure or obstructed air filters or improper combustion or diminished ignition system voltage or weak coils or worn ignition wires or improper Spark Plug gap. Motor idling periods that are extended or vehicle speeds that remain low can stop combustion deposits from being burned completely while deposit fouling caused by oil residue or coolant buildup or additives will decrease spark intensity although powdery deposits normally do not impact it unless they form a hard crust on the electrode surface.

Begin Spark Plug replacement by disconnecting the wires and turning each device by 1 or 2 notches. The cleaning process for spark plugs involves brushing off debris with air pressure or a brush followed by single plug removal into tray identification marked for each cylinder. Check the placement of individual Spark Plug washers before inspecting the Spark Plug gap for proper length which should be 1.524 mm (0.060 in). Beginning with each cylinder's specific Spark Plug the technician must perform hand torques followed by the appropriate tightening force. For utilized heads the torque value should remain at 15 n.m (11 lb ft) and for aluminum heads the value should be 20 n.m (15 lb ft) while new iron heads require 30 n.m (22 lb ft). Reinstall Spark Plug Wires as the last step in the procedure.

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

First, remove the spark plug wires and loosen each spark plug one or two turns.