With the widespread introduction of front-wheel-drive vehicles, struts have predominately replaced the use of shock absorbers. The space limitations caused by placing both the engine and transmission in the front of the car create a need for struts. By combining the shock and suspension spring into a compact unit, the resulting strut saves space and simplifies the front-end suspension design. Struts fail because of heat. They absorb bumps and bounces, convert them into heat and, over time, fail.
Turn the front wheels of the car to the extreme right or left, and shine a flashlight along the body of the strut. Although you will not be able to see the top mounting area, you will see the metal tube of the strut body inside the spring --- often covered with a plastic sleeve, and sometimes shaped like a bellows. If the sleeve is covered in oil residue, the strut has begun to leak. Replace it.
Start the car, and have an assistant steer the front wheels back and forth. If the strut assembly jumps or around or is excessively noisy as your assistant turns the wheel, the upper strut bearing plate has become defective and needs replacement. Replace both the strut and plate as a unit.
Place a knee on either the right front or left front bumper, and press down. Back away from the car, and notice the dampening effect of the strut. If it fails to rebound, the strut is sticking inside the housing. If the car oscillates several times before it dampens, the strut is no longer working. Repeat this process for the other corner. Replace the struts if they fail to dampen the rebound quickly and smoothly.
Test-drive the car on an isolated road to determine how the car handles under stressful conditions. Rock the vehicle with quick steering motions, and notice how the car manages the sudden changes. Go over bumpy areas and sharp inclines. If the suspension feels sluggish, fails to recover quickly or scrapes the road over minor bumps and inclines, replace the struts.
