Worn joints likely cause of strange clicking noise

by Jim KerrBackyard Mechanic . Oct 28 2016
FotolioA constant velocity joint, covered here with a protetcive rubber boot, allows the wheels to steer and transmit power from the transmission to the wheel at the same time.

Fotolio

A constant velocity joint, covered here with a protetcive rubber boot, allows the wheels to steer and transmit power from the transmission to the wheel at the same time.

Question: There’s been a worrisome clicking noises in my 2013 Mazda3 that worry me a bit. The noise sounds almost like an old mechanical typewriter. The car ticks away rhythmically, but only when I turn a corner. If I’m driving faster, it will tick faster. When I’m driving straight down the road, it’s quiet. The sound seems to be coming from the front, but I’m not sure. What do you think it could be?

Answer: I think you have given me enough clues to narrow the problem down. It sounds like the clicking may be coming from one of the outer axle shaft constant velocity joints.

These joints allow the wheels to steer and transmit power from the transmission to the wheel at the same time. They are a flexible coupling with an inner race, an outer race and several large steel balls connecting the two races together. Both races have concave grooves in them that hold the balls in place. When you are driving straight ahead, the balls remain fairly stationary in the grooves, but when you turn a corner, the angle of the joint causes each ball to move back and forth from one end of the groove to the other end of the groove.

In an unworn joint, the balls roll smoothly along the groove. Dirt or water in the joint wears the groove, mostly in the center where the balls sit as the vehicle is being driven in a straight line. Then when you turn a corner, the balls now roll back and forth across the worn spot and create a clicking sound. As the joint becomes even more worn, you will likely be able to feel the clicking action in the steering wheel.

The joint is lubricated by grease and protected by a flexible boot. If no dirt or water gets into the joint, it can last sometimes for the life of the vehicle, but if the boot cracks and dirt gets in, the joint can be damaged in only a few hundred kilometres. Boots can be replaced if cracked or split but often it is too late to save the joint. The repair is to replace the axle assembly.

The damaged joint on your vehicle will get worse as you drive so the axle will eventually have to be replaced, but it isn’t an emergency repair at this point. If you can feel it in the steering, the joint should be replaced soon.

Question: I have an older 2000 Buick Century that has very low mileage on it and is in very good shape. Most of the time the steering works fine but on cold mornings, when I first start the car, the steering wheel is hard to turn. If I let the engine run for a few minutes, the steering is easy to turn again. What do you think the problem could be?

Answer: I have run across this problem many times. The problem is in the power steering rack (steering gear). If you take a look at the fluid colour in the power steering pump, it will have a slight greyish colour, which is caused by small particles of aluminum in the fluid from the worn rack.

The power steering works by directing fluid flow to one side or the other of a piston inside the power steering rack. When you have the steering wheel straight, the pressure of the fluid is the same on both sides of the piston. When you turn, fluid pressure is increased on one side of the piston more than the other. There is a seal on the piston and when the fluid and rack are cold, the fluid is leaking past the seal and preventing pressure from increasing on one side of the piston. This makes the system act like there is no power steering. Once the fluid and seal warms up, it tends to seal better so the power steering returns.

The only repair solution is to replace the worn steering rack with a new unit. At the same time, the fluid needs to be flushed from the power steering pump and lines or the aluminum particles in the fluid will wear the new rack.

james.kerr@sasktel.net