GM 12592619
Spark Plug

The first step to replace spark plugs consists of shutting off the ignition while removing both sets of Ignition Coil assemblies. The engine needs to cool before work starts since removing hot spark plugs may lead to thread seizure that damages the Cylinder Head threads. After cleaning the Spark Plug recess area make sure to utilize a thread chaser before new plug installation since contaminating the head threads can obstruct proper location of new plugs. Check all spark plugs after extracting them from the engine. The correct engine components for the vehicle need to be used since improper plugs either hotter or colder than specified damage the engine. A round feeler gauge must check the gap of new and reconditioned spark plugs before installation since pre-set gaps might alter during handling and wrong gap settings may cause engine performance problems or engine damage. Compare the measurement of the Spark Plug gap to manufacturer specifications before making adjustments when needed. The installation requires a smooth thread insertion into the Cylinder Head until the plug achieves total seat position and requires a thread chaser to clean the way. Secure each Spark Plug into the engine by torquing it to 15 nm (11 lb ft) while putting back both Ignition Coil assemblies.

Check the gap of all new and reconditioned spark plugs with a round feeler gauge to ensure it meets the spark plug gap specification.

Ensure that the spark plug threads smoothly into the cylinder head and that the plug is fully seated.

The ignition coils.

Thread Chaser.

Inspect the spark plugs.

Use a thread chaser if necessary.