It is common for older or poorly maintained cars to squeak, groan and chirp when driven. Squeaking typically means that there is metal-to-metal contact due to worn out parts or insufficient lubrication. Diagnosing a squeak starts by taking a close look underneath your car and checking components for damage or wear.
Hood Latch and Hinges
Not all suspension squeaks actually come from the suspension. Frequently, the squeaking can from a loose hood or a dry hood latch, particularly in vehicles with long, heavy bonnets. Open your hood and look where the hood meets the car's body. Chances are there will be some rubber stoppers that normally sit against the hood when closed. These can be raised by turning them counter-clockwise. Turn all the stoppers 1 or 2 full turns counter-clockwise, then place a dab of grease on the top of the stopper. Use a lubricating spray such as WD-40 or silicone grease and spray the hood latch mechanism and the hood hinges. Close the bonnet and go for a test drive to see if this has cured your squeak.
Sway Bar Bushings
The biggest cause of squeaking in a suspension is worn bushings, particularly in sway bars. Not only do sway bar bushings wear out, they get hard with age, which also causes squeaks. This can manifest itself as squeaking when travelling over even slight road imperfections. The sway bar is a metal bar that connects the left and right side of the suspension to improve handling. Check to see if there is "play" in the sway bar bushings. They should be snug and tight, and the sway bar itself should not be loose. If your vehicle has 70,000 or more miles, chances are the rubber bushings have become old and hard. You can spray or apply grease to them to see if this cures the squeak, but it will be a temporary fix. In order to eliminate sway bar squeak, you will need to replace the bushings with either new factory pieces, or aftermarket units.
Suspension Ball Joints
Examine the dust boot that covers the ball joints to see if it is torn or missing, and if the ball joint appears dry or worn. Ball joints connect the steering knuckles on a truck or car to the control arms. When you turn the wheel, the knuckle pivots in the ball joint. These wear down over time and typically need replacement every 70,000 to 150,000 miles depending upon vehicle use. If the dust boot is torn or missing, this will accelerate wear. Worn ball joints can make a squeaking or groaning sound when the car is moving.
Since squeaking is often caused by metal-to-metal contact, thoroughly examine your suspension and underbody from underneath the car. Look for any worn points, damaged components, or loose hardware, as these are the typical causes of squeaks. Use grease to make sure moving parts are well-lubricated.