Drive Axle Assembly Leak Inspection
What is a drive axle?
Drive axles are responsible for transmitting power from the differential to the wheel hub.
How does a drive axle work?
There is no set replacement schedule for stabilizer bar bushings, through most vehicles will need to have them changed at some point. A good time to replace the stabilizer bar bushings is when they being to make a squeaking sound when the vehicle is going over bumps or through turns, or when the sway bar links are being replaced.
What are the symptoms of a bad drive axle?
The symptoms of a drive axle leak are very clear. For straight axle vehicles, the backing plate for the brakes will have fluid draining on, or from behind it. If the leak has entered the drum brake assembly, the brakes may not function with the expected amount of stopping force. Leaks may also develop from the bottom of the differential cover, or input shaft seal. Both of those leaks will develop a drop from the bottom of the differential housing. For CV axles, the leak is easy to spot, as axle grease will coat everything around the torn boot. If the transmission or differential output seal is leaking, the axles may sling that fluid around the wheel wheel and undercarriage while driving.
Can I drive with a bad drive axle?
Driving with an axle leak is not particularly dangerous or hazardous to the vehicle, except in the case that the brakes are not performing properly due to fluid contamination. Vehicles with braking issues should not be driven. Concern should be taken for how long a component has been leaking. If the leak has continued long enough, the leaking component may be in danger of mechanical failure. If any mechanical noises are heard from the transmission or differentials, the vehicle should be inspected as soon as possible.
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How often are drive axles replaced?
Differential cover fluid leaks are commonly repaired in the process of servicing the differentials for factory scheduled maintenance. Wheel seals, differential and transmission output seals, and CV boots fail at a significant rate. Most vehicles will need one or all of these repairs at some point in their serviceable life.
How are defective drive axle assemblies diagnosed?
Inspecting for axle leaks is very straightforward, diagnosis only requires simple observation while the vehicle is on a lift. If any leaking or seepage is detected, the seal or boot must be changed.
How are drive axles replaced?
Replacing a wheel seal requires the differential cover to be removed and axles to be disconnected from the differential. Then the wheels, tires, brake drum or caliper and rotor, and axle must be removed. The seal is pulled, and replaced, and the axle housing can be reassembled. For the pinion seal, the drive shaft must be removed, then the pinion nut must be marked and removed. The seal is replaced, and the pinion nut preload will be set. After both repairs, the differential will be refilled with the appropriate type of gear oil. CV boot replacement or output seal replacement require the wheel and the lower ball joint to be removed to free the CV axle. Then the CV boot or output seals can be replaced, and the CV axle may be installed. If the CV joints are popping while the vehicle is turning, the CV axle should be replaced. Then the ball joint can be installed, and the axle nut can be torqued to specification.
RepairPal recommendations for when the drive axle assembly fails
We recommend replacing a leaky axle seal or boot as soon as possible. As time passes, the leak will become larger, and there is a very limited amount of gear oil and axle grease to protect expensive components.
What to look out for with a drive axle assembly
There are many types of differentials on modern vehicles. Some are traditional clutch-type, limited slip differentials, or are electronically controlled, torque-vectoring types. The gear oil used in these differentials will vary by manufacturer, and filling with the wrong type of fluid can cause damage to the expensive differential units, requiring replacement.
Can I perform a drive axle assembly inspection myself?
Anyone can inspect an axle for leaks. The undercarriage of the vehicle is normally very dry and dusty. When a leak occurs, the oil will create a dark, wet spot. This will enable anyone to locate the leak, and decide whether the mentioned repairs are within their abilities. Only a very experienced DIYer should attempt these repairs, as there are assemblies that require experience, skill, and training to properly service.
