Resolving Tandem Pump Stickiness and Fan Direction on a Case 40XT Skid Steer

[MikePhua]

The Case 40XT and Its Design Evolution
The Case 40XT skid steer loader was introduced in the early 2000s as part of Case Construction Equipment’s XT series, which aimed to modernize compact equipment with improved hydraulic performance and operator ergonomics. Case, founded in 1842, had long been a leader in loader-backhoe and skid steer innovation. The 40XT featured a 60-horsepower diesel engine, a rated operating capacity of 1,500 pounds, and a hydraulic flow of 16.2 gallons per minute—making it ideal for land clearing, grading, and light excavation.
By 2003, the 40XT had gained traction among contractors and landowners for its reliability and ease of maintenance. Its tandem hydraulic pump system allowed for precise control of drive and loader functions, but like many machines of its era, it was vulnerable to moisture intrusion and seal degradation over time.
Diagnosing Sticky Joystick Movement
After sitting idle for several weeks in cold weather, a 2003 Case 40XT began exhibiting sticky movement in the right-hand joystick, responsible for forward and reverse motion. Initial inspection ruled out linkage issues, as all external components moved freely. The problem was traced to the internal shaft of the tandem pump, where the joystick linkage connects.
Upon disassembly, the servo spool, sleeve, and guide were found seized together—likely due to moisture ingress and rust formation. This internal binding caused jerky motion and resistance, even when the machine was shut down. Cleaning the components with wire brushes and brass tools helped, but pitting remained on the sleeve, raising concerns about long-term reliability.
Replacing Seals and Rebuilding the Servo Spool
To address the issue, new O-rings and seals were ordered for the spool assembly. Case lists two different tandem pump models for the 40XT, each with unique seal part numbers. In this case, seals for pump model 404281A1 were used, though uncertainty remained about compatibility due to ambiguous serial number matching.
The spool was reassembled carefully, ensuring correct orientation—since the spool is directional and must not be installed 180 degrees out. Once installed, the joystick movement became smooth, but a new issue emerged: the machine began creeping forward when the lap bar was lowered, even with the joystick in neutral.
Correcting Hydraulic Creep with Spring Plate Adjustment
Hydraulic creep in skid steers is often caused by misalignment in the servo spool’s neutral position. Case’s tandem pump includes a spring plate that sets the preload on the spool. This plate is held in place by a shouldered lock bolt, which leaves an impression on the mounting surface.
To eliminate the creep:

• Disconnect the joystick linkage
  
• Slightly rotate the spring plate to adjust spool preload
  
• Re-secure the plate in a new position
  
• Test for neutral stability and fine-tune as needed
  

This adjustment resolved the creeping issue entirely. The machine returned to smooth, predictable operation, and the owner proceeded to order seals for the left-side pump to match the restored feel of the right.
Fan Direction and Engine Compartment Debris
The second issue involved debris accumulation in the engine compartment during honeysuckle clearing. Leaves and sticks were being drawn into the radiator area, prompting the owner to consider reversing the fan direction.
However, simply flipping the fan blades does not reverse airflow. Fan pitch and rotation are engineered to move air in a specific direction. Case does not offer a pull-style fan for the 40XT due to concerns about exhaust gases being drawn into the cab area.
For operators seeking reversible airflow, aftermarket solutions like Cleanfix or Flexxaire fans offer electronically controlled blade pitch reversal. These systems allow the fan to periodically reverse direction, blowing debris out of the radiator fins without manual intervention. While more expensive, they are increasingly popular in forestry and agricultural applications where airborne debris is constant.
Preventative Maintenance Recommendations
To avoid future servo spool issues and improve machine longevity:

• Store equipment in dry, insulated environments during winter
  
• Periodically operate hydraulic controls to prevent seal drying
  
• Apply dielectric grease to electrical connectors and linkage pivots
  
• Replace hydraulic fluid and filters every 1,000 hours or annually
  
• Inspect tandem pump components for rust and wear during service intervals
  

For fan performance:

• Clean radiator fins weekly during heavy brush work
  
• Install mesh screens or debris guards around the engine bay
  
• Consider upgrading to a reversible fan system if operating in high-debris zones
  

A Field Story from Indiana
A contractor in southern Indiana experienced similar joystick stiffness after winter storage. Upon inspection, the servo spool was rusted and partially seized. Rather than replacing the entire pump, he rebuilt the spool assembly with new seals and adjusted the spring plate. The machine returned to full function, and he later installed a Flexxaire reversible fan to combat soybean chaff during harvest season. The upgrade reduced radiator cleaning time by 80% and extended belt life significantly.
Conclusion
The Case 40XT remains a dependable skid steer, but like all hydraulic machines, it requires vigilance in maintenance—especially after periods of inactivity. Sticky joystick movement and hydraulic creep can be resolved with careful spool inspection and spring plate adjustment. For operators battling engine bay debris, fan upgrades and airflow management are essential. With thoughtful service and a few strategic upgrades, the 40XT can continue clearing land and moving material with precision and ease.