How do you know if a CV joint is failing?

The most common sign of a failing CV joint is a rhythmic clicking or cracking noise when you turn the steering to full lock, such as pulling out of a junction or manoeuvring in a car park. It tends to get faster as the car speeds up and goes away when you drive straight.

CV stands for constant velocity. These joints sit at each end of a driveshaft and let power reach the wheel while the suspension moves and the wheel steers. They are packed with grease and sealed by a rubber gaiter. When that gaiter splits, the grease escapes, dirt gets in and the joint wears quickly.

What are the symptoms of a bad CV joint?

The outer joint, next to the wheel, usually announces itself first. Listen for clicking on a tight turn, and check whether it is louder on one lock than the other, as that can point to the affected side.

An inner joint, nearer the gearbox, wears differently. A worn inner joint is more likely to cause a shudder or vibration when you accelerate, which can ease off when you lift your foot.

• Clicking or clacking on full steering lock
• Vibration under acceleration
• Grease flicked around the inside of the wheel arch
• A clunk when you change between accelerating and coasting

What causes a CV joint to fail?

Nearly always the cause is a damaged gaiter. Rubber perishes with age, heat and road dirt, and a split lets the grease out. Once the joint runs dry and gritty it wears, and the clicking begins.

Impact damage from potholes and kerbs can also bend or crack components, and a joint that has been worked hard on rough rural lanes may wear sooner. Frequent full-lock turns put extra load on the outer joint, which is why it often goes before the inner one.

What can I check myself before driving to a garage?

With the car parked safely and the engine off, turn the steering to full lock and look behind the front wheel with a torch. You are looking for a black rubber concertina boot on the driveshaft. Cracks, splits or a slick of dark grease thrown around the surrounding parts are all warning signs.

Do not put your hands near the wheels or underneath a car that is only supported by a jack. If you cannot see clearly, leave it to a garage with a ramp. A torn gaiter is also something an MOT tester can fail, so it is worth looking at before test time.

What does a garage do about a clicking CV joint?

We start by finding out which joint is making the noise and whether the gaiter is split, the joint is worn, or the noise comes from somewhere else such as a wheel bearing or suspension part. Those faults can sound similar from the driver's seat.

If the gaiter has only just split and the joint is still sound, a new gaiter and fresh grease may be possible. If the joint has run dry and is worn, the driveshaft or joint normally needs replacing. We cannot say which applies until the car has been inspected. The cost depends on the vehicle, which side is affected and whether parts are single joints or a complete shaft.

When should I stop driving with a CV joint problem?

A clicking joint can carry on for some time, but it will not mend itself. A badly worn joint can eventually break, and then the car loses drive to that wheel and may stop suddenly.

Stop driving and get advice if you hear loud clunking, feel strong vibration at speed, or notice the car losing drive. Short, gentle trips to a garage are usually safer than waiting for it to fail on a faster road.