Hydraulic jacks are essential tools in garages, repair shops, and service stations. As with all hydraulic equipment, long-term use may lead to operational issues that affect lifting performance and safety. Understanding common symptoms and troubleshooting methods can help users restore proper function quickly and avoid unnecessary downtime.
Below, we summarize the most frequent problems found in hydraulic jacks and explain how to diagnose and resolve them step by step.
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1. Jack Fails to Rise (or Cannot Reach Normal Height)
When a hydraulic jack stops rising or fails to reach the expected lifting height, it often indicates insufficient hydraulic oil.
The first step is to check the oil level and top it up as needed. If the jack still doesn’t rise after adding oil, the issue may involve the oil return valve:
• The valve needle may not be closing tightly
• Tighten the valve needle slightly to ensure proper sealing
If no oil leakage is found around the pressure rod, yet the jack still cannot rise, the sealing ring may be worn or damaged, requiring replacement.
This issue typically reflects poor sealing or air entering the hydraulic chamber, both of which directly reduce lifting strength.
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2. Jack Jitters or Shakes During Lifting
A jack that lifts intermittently or shakes during operation usually indicates poor valve sealing—specifically, a loose oil return valve needle.
When the valve is not sealed, hydraulic oil flows back instead of maintaining stable pressure, causing shaking.
To solve this:
• Tighten the valve needle to improve the seal
• Inspect for external oil leakage
• If shaking continues, replace the sealing ring to restore stable pressure buildup
Jittering is one of the earliest signs that internal sealing is weakening, so timely inspection is important.
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3. Jack Cannot Rise Under No Load
If the jack fails to rise even with no load, follow this sequence:
Step 1 – Check Oil Level
Add oil if it is insufficient.
Step 2 – Remove Air from the System
Air trapped in the hydraulic chamber can prevent pressure buildup.
To exhaust air:
1. Loosen the oil return valve
2. Remove the oil plug
3. Step on the jack base while pulling the jack up and pressing down repeatedly
4. Repeat several times until air is expelled
After exhausting air, tighten the oil plug and valve, then test again.
Step 3 – Inspect Oil Return Valve and Valve Seat
If the jack still cannot rise:
• Remove the return valve
• Check whether the valve cone and the seat fit correctly
• Clean out any dirt or debris
• Replace the valve if pits or grooves are present
Step 4 – Check Additional Components
Inspect whether:
• The oil inlet valve seals correctly
• The top rod sealing ring is worn or detached
Replace any damaged parts promptly to restore proper operation.
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4. Oil Leakage
Oil leakage is among the most obvious symptoms of hydraulic jack malfunction.
Common leakage points include:
• The joint between the cylinder and the seat
• Around the top rod
• Threaded areas of the oil return valve
• The oil plug of the filling port
• Around the pressure rod
In most cases, oil leakage occurs because sealing gaskets have aged or been damaged.
The solution is simple: replace the faulty gasket or sealing ring to prevent pressure loss and ensure safe operation.
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Conclusion
Hydraulic jacks rely on a closed, pressurized system to operate effectively. Most issues—failure to lift, jittering, inability to rise under no load, and oil leakage—stem from oil shortages, valve sealing problems, trapped air, or worn sealing components.
By following structured troubleshooting steps and replacing sealing parts when needed, users can restore jack performance quickly and extend equipment life.
Regular inspection, timely maintenance, and proper handling are key to ensuring your hydraulic jack remains safe, stable, and reliable for long-term use.