Bad Strut Symptoms – 8 Signs It Is Time for Replacement

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Struts wear out gradually, which is why most drivers do not notice the decline until the ride feels completely different from when the car was new. A set of struts that have passed eighty thousand miles on a Toyota Camry or Honda Accord will have lost most of their damping ability, yet the car still drives well enough that the owner delays the repair. The eight symptoms below show up long before the strut leaks oil, and catching them early saves tires and brakes.

What the driver feels

The front end clunks or knocks over small bumps, expansion strips and potholes.
The car leans or sways noticeably in corners compared to when it was new.
The nose dives forward when braking hard from highway speed.
The front tires show cupping or scalloping on the edges of the tread.
The car wanders on the highway and needs constant small steering corrections.
The bounce test at a front corner settles slowly, taking three or four bounces.
Fluid is visible weeping down the sides of the strut body.
The front of the car sits lower than it should, especially on one side.

How strut wear progresses over miles

Struts lose damping as the internal seals wear. On a Ford F-150 or Chevrolet Silverado, the piston rod seal that holds oil inside the pressure tube hardens after years of heat cycles, and a small amount of fluid seeps past the seal with every stroke. The oil level drops, the valving becomes spongy, and the spring is no longer controlled. What used to be one bounce after a speed bump becomes two or three.

Worn struts also let the tire move around on the road. On a Nissan Altima or Hyundai Sonata, a tired strut allows the wheel to skip and hop over small bumps, which polishes the tire tread into a cup or scallop pattern. The cupping starts on the inner shoulder and spreads across the tread, and the tire makes a droning noise that sounds almost like a bad wheel bearing. By the time the noise is noticeable, the tire is already ruined.

Checking strut condition at home

Push down hard on each front corner of the car and release. A good strut settles in one and a half bounces; three or more means worn.
Walk around the car and look at each strut body for oily film running down the tube, which means the seal has failed.
Look at the front tires for cupping or scalloped wear on the tread edges, which follows worn struts.
Measure the front ride height from the fender lip to the center of the hub on both sides and compare.
Road test over a known bumpy road and count the number of bounces after each dip.
Safety note: Support the car on jack stands if you inspect under the wheel well, and never put any part of your body under a vehicle supported only by a jack.
Check the strut mount top for play by pushing on the top of the tire while watching the mount for movement.
Compare left and right sides: a one-sided sag or clunk usually means that strut has failed internally.

What replacement involves

Replace struts in pairs on the same axle. One worn strut makes the new one on the other side work twice as hard.
Choose between a complete strut assembly (spring, mount, strut cartridge) or a cartridge insert. The assembly is easier for DIY and includes fresh top mounts.
Always torque the top strut mount nut with the vehicle sitting at normal ride height, not on a lift, to avoid pre-loading the mount bushing.
Replace the strut mount and bellows at the same time if you are replacing the cartridge, because the spring has to come out anyway.
Finish every strut job with a four-wheel alignment, because the strut holds camber and caster on most front suspensions.