What is the Differential Output Seal all about?

Your vehicle’s engine produces power and transmits it in a straight line through the crankshaft into the transmission. The power that comes through the transmission is in the same straight line as the engine, yet somehow needs to change 180 degrees to power the wheels. The differential is a component in your vehicle that changes the direction of the propulsion from a longitudinal orientation to a lateral one, and it can also provide a fixed gear ratio change. The differential contains a pinion gear and side gears that rotate in fluid to solidly transfer the power 180 degrees. Axle shafts run from the differential to each wheel in a couple different designs, yet each needs a way to contain the oil inside the differential assembly. The axle shaft runs through an output seal in the differential that allows the shaft to rotate without losing the lubricating oil inside. If the axle seal leaks and the fluid escapes, the differential won’t be properly lubricated and the gears and bearings can overheat and seize, causing extensive damage and rendering your vehicle unfit to drive.

Keep in mind:

• A differential doesn’t have a dipstick to check fluid level in most instances. If there is a leak present, it is nearly impossible to know how much fluid remains.

How it's done:

• The differential output seal is verified that it needs to be replaced. The vehicle is lifted and supported on jack stands.
• The CV axle is removed and defective differential output seal is removed using a seal removal tool.
• The new differential output seal is installed using a seal installer then the CV axle is reinstalled.
• The differential is refilled tested for leaks. The vehicle is removed from the jack stands.
• The vehicle is road tested to ensure proper operation of the differential output seal.

Our recommendation:

The differential fluid requires replacement at regular intervals, usually around every 25,000 miles. Have the differential output seals inspected for leaks at this time, and if during any other regular maintenance inspection an output shaft seal is found to be leaking, have it replaced by one of our expert technicians.

What common symptoms indicate you may need to replace the Differential Output Seal?

• Fluid leaking onto the ground under your vehicle
• Loud whining or grinding noise that increases with speed heard when driving

How important is this service?

The differential output seal is important to the lubrication of the internal gears in the differential, though most leaks start out small. If you have just noticed or been notified of a small leak, you have some flexibility in timing to replace it. If the differential leak is major, have it repaired soon to prevent additional internal damage.