What causes the shock absorber to have resistance when compressed but not rebound?

[VonJameson]

The reasons why a shock absorber has resistance when compressed but does not rebound are as follows: Since the rebound force of the shock absorber is provided by the shock-absorbing spring absorbing road vibrations and impacts, once the shock-absorbing spring is damaged, it will greatly affect the rebound force of the shock absorber. Below is relevant information about shock absorbers: Working principle: The working principle is that when the frame (or body) and axle experience relative movement due to vibration, the piston inside the shock absorber moves up and down, causing the oil in the shock absorber chamber to repeatedly flow from one chamber to another through different pores. Purpose: To accelerate the attenuation of frame and body vibrations and improve the vehicle's ride smoothness (comfort), most vehicles' suspension systems are equipped with shock absorbers.

[IrisRose]

I've been in auto repair for over a decade, and when I encounter shock absorbers that resist compression but fail to rebound, it's usually a classic sign of either leaked fluid or internal piston seizure. Shock absorbers rely on hydraulic pressure to dampen vibrations – once the fluid leaks out, the piston gets stuck in the compressed position and can't spring back. In some older vehicles, prolonged valve wear can also cause them to lock up. The check is straightforward: look for oil stains or rust marks on the exterior of the shock absorber, and press down on the spring area near the tire to test. Don't ignore this issue – driving without proper damping feels like having no suspension at all, leading to severe bumpiness, handling difficulties, and significantly increased skid risks during turns. I recommend stopping driving immediately and getting professional replacement. For routine maintenance, regularly checking for balanced tire pressure can help delay aging.

[Florence]

I had this exact experience with my car before. After running for just over six years, one day I noticed the shock absorber felt stiff when pressed down and wouldn't bounce back when released, just like a dead snake. This was mostly because the oil inside the shock absorber had leaked out completely, likely due to the aging of the sealing rings causing the oil to seep away. Sometimes, it's because the piston rod is bent or jammed with accumulated dust, getting stuck when force is applied. I first checked the car's balance myself: the car wobbled noticeably on flat roads, especially when going over speed bumps, making constant thumping noises. Don't try to save money by making do with it—send it to the repair shop right away. The mechanic diagnosed it in no time, replaced the part, and it was back to normal. A reminder to everyone: when washing your car regularly, take a moment to inspect the undercarriage. Any shortage of fluids or damage can be spotted early, preventing breakdowns or accidents on the road.

[Santana]

The shock absorber has resistance when compressed but does not rebound, and the common reasons are as follows: First, oil leakage—without oil, it cannot rebound with force; second, internal valve blockage, such as spring rust or debris clogging; third, piston seal failure or deformation, with the piston rod misaligned and stuck in the middle position; fourth, external impact damage, such as hitting a large pothole that bends components. The inspection method is simple: check for oil leakage or dents on the outside of the shock absorber. For prevention, drive less on bumpy roads and perform regular maintenance. Address issues promptly to avoid worsened handling and accelerated tire wear.

[TylerDella]

As a regular car owner, I also wondered why the shock absorber was hard to compress but wouldn’t rebound when I first learned to drive. Later, I found out it’s due to issues with the internal hydraulic system: if the oil leaks or the valve fails, the piston gets stuck at the compression point and can’t move. It’s like a bicycle pump with an air leak—press it down, and it won’t spring back. You’ll feel the car body unstable and the ride harsh. Take it to a repair shop—the mechanic will test the spring tension and replace the oil seal. Don’t delay; driving on the highway with this issue can cause dizziness from excessive swaying, which is a safety hazard.

[RachelLynn]

From a safety perspective, a shock absorber not rebounding means the damping function has failed: there's resistance when compressed because the spring is working, but the lack of hydraulic pressure causes it to get stuck and unable to rebound. This could be due to oil leakage or internal component wear and aging. The car will experience severe bumpiness, poor tire grip, increased risk of skidding during turns, and longer braking distances. Don't wait for an accident to address it: stop driving and inspect the shock absorbers' condition—if there are oil stains or deformation, send it for repair immediately. It's recommended to perform maintenance every six months, thoroughly cleaning the undercarriage to ensure the shock absorption system remains intact, as this is fundamental to safe driving.