Sudden failures of constant velocity joints are rare, but CV joints do wear out and may fail as a result of loss of lubrication or grease contamination (usually due to a failed boot). A CV joint that is failing usually produces various symptoms:

A popping or clicking noise when turning. This almost always indicates a worn or damaged outer CV joint. A quick way to verify this condition is to put the car in reverse, crank the steering wheel to one side and drive the vehicle backwards in a circle (check the rearview mirror first!). If the noise gets louder, it confirms the diagnosis and the need for a new joint or replacement shaft assembly

.A "clunk" when accelerating, decelerating or when putting the transaxle into drive. This kind of noise can come from excessive play in the inner joint on FWD applications, either inner or outer joints in a RWD independent suspension, or from the driveshaft CV joints or U-joint in a RWD or 4WD powertrain. Be warned, though, that the same kind of noise can also be produced by excessive backlash in the differential gears. A quick way to verify the diagnosis here is to back the vehicle up, alternately accelerating and decelerating while in reverse. If the clunk or shudder is more pronounced, it confirms a bad inner joint. A humming or growling noise. Sometimes due to inadequate lubrication in either the inner or outer CV joint, this symptom is more often due to worn or damaged wheel bearings, a bad intermediate shaft bearing on equal length halfshaft transaxles, or due to worn shaft bearings within the transmission.. A shudder or vibration when accelerating. Excessive play in either the inboard or outboard joints can sometimes cause this, but the most likely cause is a worn inboard plunge joint. These kinds of vibrations can also be caused by a bad intermediate shaft bearing on transaxles with equal length halfshafts. On FWD vehicles with transverse-mounted engines, this kind of vibration can also be caused by loose or deteriorated engine/transaxle mounts. For this reason, the rubber bushings in the upper "torque strap" or "dog bone" on these engines should also be inspected to rule out this possibility.

CV JOINT INSPECTION & BOOT REPLACEMENT

The first things that should always be checked are the boots around all four CV joints on a FWD car or van. The boots should be inspected for splits, cracks, tears, punctures, abrasion damage and loose or missing clamps. Damaged boots should be replaced as soon as possible because continuing to drive with a damaged boot is asking for trouble. If the grease inside has not been lost or contaminated yet, it soon will be. This will quickly ruin the constant velocity joint if it has not already suffered damage.

Replacing a damaged boot with a one-piece OEM style or aftermarket boot is a job because the halfshaft must be removed from the vehicle. Axle removal is necessary because the CV joint must first be pulled off the shaft so the new boot can be installed. An alternative here is to replace the damaged boot with a split-boot repair kit.