The following information describes these noises:
Rhythmic Ticking: This is a rhythmic ticking that can be heard during deceleration. The noise is usually, but not limited to, heard coming from around the passenger side of the vehicle. The noise is from the fuel injectors firing (one injector per deceleration and not always the same injector) and is a normal function of the engine and calibration system.
Parts Cycling Closed and Open: Some noises may be coming from under the hood after the engine has been turned OFF. You may notice that they are the same noises almost every time the engine is turned OFF. These noises seem to be coming from the turbocharger and/or the intake airlow valve. The intake airflow valve is a throttle plate actuator and is used to achieve high exhaust gas recirculation rates. These parts will cycle through their complete normal operating ranges after the engine is turned OFF. This is a normal operating condition.
Diesel Engine Tick: Diesel engine tick is present in all diesel engines produced in the last 20 years and does not have any impact on engine reliability and durability. It may be more noticeable on the 6.6L L5P because of the major reduction in combustion background noise. This occurs at idle and may seem to be louder when standing just behind the driver’s front wheel. The noise may be more noticeable in the first 20% of engine oil life. Dealers should not attempt to compare any customer vehicles exhibiting this noise with other similar vehicles as the noise is different from vehicle to vehicle and this may lead to the incorrect conclusion that the vehicle has a condition. The noise is a normal operating characteristic and has no short or long term effects on the engine. DO NOT attempt repairs for this noise.
DEF Injector Noise: A tick noise may be heard coming from under the vehicle and typically it is heard at low vehicle speed and especially next to a building, such as when going through a drive through. The noise is from the DEF Injector and is considered a normal operating condition.
The information found in this bulletin can be shared with customers that may inquire about this condition. In the event they have additional questions or concerns, please advise them to contact Customer Assistance.