The Ford Explorer has a transfer case that can experience several possible problems. Fortunately, most of these issues are repairable by the typical owner. Proper preparation is a good way to make the experience more enjoyable for all involved.
When the transfer case is difficult to shift, there are a few possible causes. Loose parts within the transfer case or within the modules that control it can cause this problem. Additionally, the lubrication in the transfer case should meet or exceed the manufacturer's specifications and be at the correct levels.
Usually a noisy transfer case is the result of adding the incorrect grade of lubricant or insufficient levels of the lubricant. It should be changed and refilled with the correct grade of lubricant to the correct levels.
This condition can be caused by the transfer case not being fully engaged. Also, broken, loose or defective parts can make this type of "slip" happen, such as the shift fork being cracked.
The transfer case can be overfilled, causing a leak. There is a vent in the case that may become clogged or jammed closed. Additionally, the output shaft has a seal that can become damaged.
