6.6L LB7 LLY Drive Belt Chirp When the Engine is Shut Off - keywords belt chirp noise engine off

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

An accessory drive belt chirp may be noticed when the engine is shut off.

THIS IS A NORMAL CONDITION FOR DIESEL ENGINES.

Drive belt chirp when the engine is shut off is a characteristic of all GM diesel engines.

Due to the higher compression in a diesel engine, the crankshaft comes to a rapid stop when the engine is turned off. This will induce a drive belt chirp.

Drive belt chirp when the engine is shut off may or may not occur. There are many variables that will affect belt chirp. This may cause one belt chirp to be worse then another. Variables will include temperature, humidity, engine compression, internal engine friction, belt condition, tensioner spring tension, tensioner position at time of engine stopping, pulley condition, drag imposed by accessory drive components, and where the engine is when it is shut off.

Do not attempt repairs for drive belt chirp if it occurs when the engine is shut off.

Complete the current SI diagnostics for any drive belt noises that occur while the engine is running.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.