Checking Hydraulic Fluid on a Case 1840 Skid Steer the Right Way

[MikePhua]

The Case 1840 and Its Hydraulic System
The Case 1840 skid steer loader was introduced in the early 1990s and quickly became one of the most popular compact machines in North America. With a rated operating capacity of 1,400 pounds and a 51-horsepower Cummins diesel engine, the 1840 was built for versatility and durability. Case Corporation, founded in 1842, had already earned its reputation in agricultural and construction equipment, and the 1840 further solidified its standing in the compact loader market.
The hydraulic system on the 1840 powers the lift arms, bucket tilt, and auxiliary attachments. It uses an open-center design with gear-type pumps, delivering consistent flow and pressure for demanding tasks. Maintaining proper hydraulic fluid levels is essential for performance, safety, and component longevity.
Terminology Notes

• Open-Center System: A hydraulic design where fluid circulates continuously until a valve is activated
  
• Gear-Type Pump: A pump that uses rotating gears to move hydraulic fluid under pressure
  
• Reservoir: The tank that stores hydraulic fluid for circulation
  
• Sight Gauge: A transparent tube or window that shows fluid level visually
  
• Dipstick: A calibrated rod used to measure fluid depth manually
  

Where and How to Check Hydraulic Fluid
On the Case 1840, the hydraulic fluid reservoir is located beneath the rear hood, just above the engine compartment. There are two primary methods for checking fluid level:

• Sight Gauge Method
  Most 1840 units are equipped with a sight gauge mounted on the side of the reservoir. To check:
  • Park the machine on level ground
    
  • Lower the lift arms fully
    
  • Shut off the engine and wait 2–3 minutes for fluid to settle
    
  • Observe the fluid level in the sight gauge—it should be between the upper and lower marks
    
• Dipstick Method (if equipped)
  Some models or aftermarket reservoirs use a dipstick instead. To check:
  

• Remove the dipstick cap
  
• Wipe the dipstick clean
  
• Reinsert fully and remove again
  
• Read the fluid level against the marked range
  

If the fluid is below the recommended level, add Case-approved hydraulic oil slowly, checking frequently to avoid overfilling. Overfilled systems can cause aeration, heat buildup, and seal damage.
Common Mistakes and Preventative Tips
Operators sometimes misread fluid levels due to:

• Checking with arms raised, which draws fluid into cylinders
  
• Reading the gauge while the engine is running, causing turbulence
  
• Using incorrect oil types that affect viscosity and system pressure
  

To avoid these issues:

• Always check fluid cold and with arms down
  
• Use ISO 46 hydraulic oil unless operating in extreme cold, where ISO 32 may be appropriate
  
• Label the reservoir cap to prevent cross-contamination with engine oil or coolant
  
• Inspect for leaks around hoses, fittings, and cylinder seals monthly
  

In 2015, a contractor in Iowa experienced sluggish lift response on his 1840. After topping off the hydraulic fluid without lowering the arms, he overfilled the system. The result was foaming and erratic control. Draining and refilling to the correct level resolved the issue.
Signs of Low Hydraulic Fluid
If the fluid level drops below safe limits, the machine may exhibit:

• Jerky or delayed arm movement
  
• Whining or cavitation noise from the pump
  
• Increased operating temperature
  
• Visible bubbles or foam in the sight gauge
  
• Reduced lifting capacity
  

These symptoms should prompt immediate inspection. Running the system dry can damage pumps, valves, and actuators—repairs that often exceed $2,000.
Maintenance Schedule and Best Practices
To keep the hydraulic system healthy:

• Check fluid level weekly or before each shift
  
• Replace hydraulic filters every 500 hours
  
• Flush and replace fluid every 1,000 hours or annually
  
• Inspect hoses and seals quarterly
  
• Keep the reservoir cap clean and sealed to prevent contamination
  

For machines operating in dusty or wet environments, consider installing a breather filter on the reservoir to reduce moisture and airborne debris ingress.
Conclusion
Checking hydraulic fluid on a Case 1840 skid steer is a simple but critical task. Whether using the sight gauge or dipstick, accuracy depends on proper procedure and awareness of system behavior. With consistent monitoring and clean fluid, the 1840’s hydraulic system will deliver reliable performance for thousands of hours—lifting, digging, and grading with the strength it was built to provide.