Bad CV joint: The CV joints, or constant velocity joints, are responsible for transmitting power from the transmission to the wheels. When the hubs are locked in, more torque is transferred through the CV joints. If a CV joint is damaged or worn out, it may not be able to handle the increased torque and may produce a popping sound.
Faulty transfer case: The transfer case is the component responsible for transferring power between the transmission and the front and rear wheels. If the transfer case is faulty, damaged or worn out it can cause the popping sound.
Universal joints: The universal joints are located between the transfer case and the differential, and they allow the drive shaft to rotate at different angles. When the hubs are locked in, the universal joints may experience more stress, causing them to wear out prematurely. Worn out universal joints can cause a popping noise when the hubs are locked in.
Differential issues: The differential is responsible for distributing power to the wheels. If the differential is damaged, it can cause a popping noise when the hubs are locked in.
