How to Tell When Front Struts Need to Be Replacedby Jody L. Campbell
There are three relatively simple tests to perform on your vehicle to help you determine if the front struts should be replaced. Another consideration before performing the tests is the age of the struts and the mileage on the vehicle. Manufacturers recommend replacing the suspension components (shocks and struts) every 30,000 to 50,000 miles to optimize the performance of the suspension of your vehicle.
Jounce the front suspension for your first test. Do this by placing a knee on the front bumper and then distributing your weight to that knee. Lean your weight onto the knee and bounce the vehicle downward to get it rocking. After the vehicle is bouncing on its own, stop and step away and try to count how many times it bounces after you stopped. More than two bounces in an up and down motion is considered weak.
Take the vehicle for a drive and choose a bumpy road. Look for bounciness and poor suspension handling, and listen for a clunking noise up front. This could be an indication of the strut(s) bottoming out while maneuvering. Relatively small bumps that create clunking in the front end or strut is a clear indication of weakness.
Look at the front of your vehicle to see if one side leans in more than the other. This might be an indication there is at least one weak strut in the front.
Place the vehicle in Park on a paved, level driveway or in a garage. Apply the parking brake and place a wheel chock behind one of the rear tires. Lift the front end, one side at a time (you don't have to lift the entire axle), using the floor jack. Place the jack stand in a safe place. Inspect and touch the shaft and housing of the strut. Check for signs of the hydraulic fluid from inside the strut leaking out on the shaft of the strut. It will have an oily feel. If you live on or drive on dirt or dusty roads, caked-on dirt, sand and grime are another telltale sign it's leaking. Although you can't tell how much fluid is left inside the strut, a leaking strut won't stop leaking and should be replaced soon. Also, run your hands up and down the coil spring and check for broken or snapped springs.
Lift and check the strut on the other side. Just because one strut is or isn't leaking doesn't mean the other one will be in the same shape. However, it's always recommended to replace any suspension components in pairs.