Your car or truck’s transfer case is what allows you to utilize the four-wheel drive or all-wheel drive function of your vehicle. This extremely intricate piece of equipment requires a special type of lubricant called gear oil or gear lube. This gear oil is much thicker than engine oil, allowing a type of lubrication known as bath oiling. In this type of oiling, the bottoms of the parts being lubricated are very slightly submerged in the lubricant, allowing the thickness of the lubricant to cause it to stick to the gears as they rotate through the bath, circulating the lubricant through the system by contact transfer. Your vehicle’s transfer case may develop leaks, which if allowed to leak without repair may cause irreversible damage. In order to repair a leaking transfer case, you first have to know where the leak is. Below is a list of ways to find the leak in your transfer case.
Most automotive parts stores sell a fluorescent dye that you can add to the fluid of your transfer case. These stores will also rent a gun like lamp which, when shone along the transfer case, will point to the leak, after the vehicle has been driven for a couple of days, will cause the leak detection fluid to fluoresce and light up, leaving a trail to where the leak is originating. Run the fluorescent lamp across the whole surface of the transfer case, paying special attention to inspection and drain plus, seals and any place that case sections come together.
Tighten Drain and Inspection Plugs
Your vehicle’s transfer case will be equipped with a drain plug at the lowest point on the transfer case. This plug can sometimes work itself loose, causing a leak. This plug should be tightened every time you change the engine’s oil. Your transfer case will also be equipped with an inspection plug midway up the side of the case. This plug is used for checking the fluid levels when you perform other vehicle services. Sometimes this plug will also work itself loose between services. Remove this plug and verify the transfer case contains the proper amount of fluid and refill as necessary. Once properly filled, replace the inspection plug and tighten completely.
Not Leaking from Plugs
If after making sure both plugs are tight enough to preclude leaks, you continue to notice the transfer case leaking, you will need to clean it to facilitate a closer inspection of possible leak sources. These sources are where portions of the transfer case come together, as well as the seals. If there is a large amount of fluid and grease coating the case, you will need to use a degreaser and plenty of water to clean as much exterior contaminants from the outside of the case. Once the transfer case, including plugs, seals and case joints are clean, run the vehicle for a day and recheck. You should begin to see the leaks restarting very quickly.