Signs of the transfer case output shaft seal damage

Signs of the transfer case output shaft seal damage

The main signs of output shaft seal damage is stiffer gear changing, grating sound in the lower part of the car, and unexpected connection and disconnection of the all-wheel drive.

The ability to instantly switch from two-wheel to four-wheel (all-wheel) drive without having to stop the car and without locking the wheel couplings is an invention that many of us have long taken for granted, especially during snowfall. Most modern cars are equipped with a plug-in all-wheel drive system. The connection can be made manually by the driver using a switch or automatically, that is, when the on-board computer detects a decrease in adhesion of the wheels to the road surface due to adverse weather or bad road conditions. The mechanical unit of the car that performs this action is the transfer case, the output shaft of which transmits power to the driving axis. In some cases, the seals located between these components dry out, wear out, or are damaged. In this case, you must immediately contact a qualified mechanic to replace the seals, which will prevent further damage to the vehicle's drive system.

What is the transfer case output shaft seal?

The transfer case output shaft seal is used in the transfer cases of all-wheel drive cars, trucks, and SUVs. The transfer case has four modes of operation: rear-wheel drive, neutral, all-wheel drive with reduced gear and all-wheel drive. The design of the transfer case includes a downshift and chain transmission, the coordinated work of which allows performance of transferring power to both axles. The result of this is that the car becomes an all-wheel drive.

The output shaft connects the case to the axle. The transfer case output shaft seal is designed to prevent the transmission fluid from leaking out at the transfer case connection point via the transmission drive shaft. The seal also helps to avoid liquid leakage from the front and rear output shafts to the differentials, which allows drivers to continuously have well-oiled metal components.

Because of fluid leaking through the seals, proper lubrication of the internal components of the transfer case stops, which eventually leads to their wear and overheating. In this case, the transfer case will be a useless node that is not able to perform its function of controlling the four-wheel drive of the car. Over time, the transfer case output shaft seal may become damaged. Those signs described below will notify the driver of this. The following main signs indicate that a damaged transfer case output shaft seal must be replaced.

1. Complicated shifting

The seal helps to keep the working fluid inside the transfer case and, consequently, inside the transmission, thus ensuring its smooth and uninterrupted operation. Leakage through a damaged seal reduces the amount of fluid that is optimal for normal transmission operation. At the same time, there is also a drop in fluid pressure, which makes it difficult to change gears both for manual and automatic transmissions. If you experience some difficulty when switching to low or high gear, contact a qualified mechanic as soon as possible to check the car and fix the problem.

2. Grating sound at the bottom of the car

If the output shaft seal is damaged or worn out, unusual sounds can be heard from the bottom of the car. In most cases, the origin of these sounds is due to decreased amount of lubricant in the transfer case and, as a result, the friction of metal against metal. It is immediately clear to an experienced driver that metal screeching is a bad symptom, so when you hear the screeching from the spot where the vehicle’s transmission is located, contact a qualified mechanic as soon as possible.

3. Random connection and disconnection of the all-wheel drive, for no specific reason

In some cases, a decrease in the working fluid level may cause the all-wheel drive to be switched on and off at random during periods when only one of the modes should be supported. This is most often due to damage to the transfer case components that control this particular operation. Premature wear of these components is most likely caused by fluid leakage through the output shaft seal. If the liquid flows out through this seal, you will find a puddle of reddish liquid under the bottom of the car. This is nothing but transmission fluid, meaning that the transmission seal or gasket is damaged and must be replaced. If you find at least one of these warning signs, contact a qualified mechanic as soon as possible to replace the transfer case output shaft seal.