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

[VonEmily]

The reasons why the 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. The following is a related introduction to shock absorbers: 1. Working principle: The working principle is that when the frame (or body) and axle vibrate and undergo relative movement, the piston inside the shock absorber moves up and down, and the oil in the shock absorber chamber repeatedly flows from one chamber to another through different pores. 2. Purpose: To accelerate the attenuation of frame and body vibrations and improve the driving smoothness (comfort) of the car, most car suspension systems are equipped with shock absorbers.

[DeRuby]

I've encountered a situation where the shock absorber has resistance when compressed but doesn't rebound. After checking around, I found it's usually because the hydraulic oil inside the shock absorber has leaked out. There's still damping but the spring assist is gone, so it can only be compressed and won't return on its own. This is quite common, especially when the car is cold in winter or with older vehicles that have been driven for a long time. I specifically asked a car-savvy friend about this, and he said to avoid carrying heavy loads regularly or frequently driving on rough roads to prevent premature shock absorber wear. If left unrepaired, the wheels may wobble, and the car body becomes unstable at high speeds, posing significant safety risks. It's recommended to quickly find a professional shop for testing - they can easily spot the problem by using tools to compress it, and then just replace the part. Remember not to skimp and buy cheap parts; matching the original factory parameters is the most reliable approach. Safety first.

[Clay]

When the shock absorber is pressed down and doesn't rebound, it's usually an internal failure. I've dealt with this many times. The main reasons are leakage of damping fluid or damage to the air seal, resulting in insufficient air pressure, so the spring can't push it back. During inspection, I first check for oil stains on the shock absorber and test the rebound force with a jack. Simple repairs like adding lubricant are basically useless; usually, it needs to be replaced. Don't underestimate this issue—it affects suspension balance, causing the car body to tilt while driving, and can even damage tires and the chassis. When driving normally, avoid overloading and potholes. During regular maintenance, have a mechanic check the condition of the shock absorbers. Replacing them every three years is the safest approach.

[OValeria]

This situation is truly dangerous. The shock absorber not rebounding increases the feeling of imbalance while driving, especially at high speeds, which is particularly risky. I've experienced a similar malfunction before—the car felt unstable and the braking distance increased. The main causes are usually lack of hydraulic fluid or a stuck internal piston, which can completely damage the spring system. If you encounter this, slow down immediately and pull over—do not continue driving. For repairs, go to an authorized shop to replace the parts; don’t attempt to fix it yourself. In terms of safety, tire wear will accelerate, and steering will become less responsive. Regular inspections are crucial. For most household cars, you should start paying attention around 20,000 to 30,000 kilometers and replace them promptly to avoid headaches later.

[LunaAnn]

I've been driving my small car for five years and have experienced shock absorber issues—they were hard when pressed down but had no bounce at all, definitely broken. Most cases turned out to be oil leaks or spring aging, where loss of lubrication caused them to seize. Once, out of curiosity, I tried spraying some lubricant, which only provided temporary relief. Eventually, I replaced them with new parts, and the ride became much more stable. The suspension felt noticeably softer, and bumps were less jarring. My advice: don’t delay. Wheel imbalance can damage rims and brake pads, and in the long run, replacing them is more cost-effective. Reducing sudden braking and avoiding potholes while driving can extend the lifespan of your shock absorbers by several years.

[SarahMarie]

The principle behind this phenomenon is internal imbalance in the shock absorber. The friction resistance during compression remains, but the reset mechanism fails, possibly due to oil leakage or structural wear. I've disassembled some and checked whether the piston rod is corroded or the oil seal is damaged. Turbid oil confirms the issue. Improper modifications are also common, with mismatched parts causing insufficient rebound. For repairs, original parts must be replaced to ensure parameter compatibility, making driving stable and safe. Avoiding rough roads can protect the shock absorbers. It's recommended to conduct a comprehensive inspection every 20,000 kilometers to prevent sudden failures.