A grease leak is probably the most common sign of a failing cv boot. Usually a problematic cv boot will produce a few symptoms that can notify the driver that attention may be required.
In some vehicles the axle shaft seal also helps to keep the axle shaft in proper alignment with the transmission.
Cv shaft boot leaking. Over time the rubber cv boot can become dry or brittle creating cracks or tears. The cv axle shaft seal is what keeps fluid from leaking out of the transmission or differential housing as the cv axle rotates when the vehicle is in motion. So when you hear those warning noises or are told that your cv axle boot is leaking it is a good idea to get the axles replaced as soon as possible.
Cv boots leaking has been found when i do oil changing. When a cv joint axle fails completely it will render the car immobile since the transfer of power to the wheels can no longer be completed. If they told you that was for an entire cv shaft assembly they are on target but check around a few other places and have them give you prices on just boot replacement not those garbage split fit it boots either a new one piece boot and a price for replacing the shafts.
The severity of the leak affects how safe it is to drive with a leaking axle seal. Usually a problematic cv boot will produce a few symptoms alerting the driver that service is required. A grease leak is the first symptom that is most commonly associated with a bad or failing cv boot.
This instructable will show how to replace a broken cv boot on a front wheel drive vehicle without disassembling it or replacing the entire shaft. If caught quickly you can usually just have the boot replaced rather than the entire joint. However the longer you drive with the boot busted the more dirt and grime contaminates the joint and the more grease leaks out.
The front axle shaft seal mounts into the axle shaft tube or the differential case depending on design and prevents the internal fluid from leaking out. When this happens the boot will leak grease onto the inside of the wheel. This guide is an inexpensive way to repair the boots only but if the boots have been torn for a while then the axle bearings may be worn out and the entire axle may need to be replaced.
When a cv boot. Over time with exposure to the elements a cv boot can become dry or brittle and crack or tear. If the leak has been present for long enough the leaking cv axle is in danger of mechanical failure.
If the problem is just a busted cv boot you might be able to drive for some time before having work done.