Case 580SK Charge Pump Filter Maintenance

[MikePhua]

Background of the Case 580SK
The Case 580SK is a wheel‑loader/backhoe hybrid built by Case Corporation, now part of CNH Industrial. Introduced in the 1980s and continuing into the 1990s, the 580SK combines a front loader with a backhoe on a robust frame. Power comes from a diesel engine (typical profiles show 70–90 hp depending on year and variant), and hydraulics are a critical part of its design. The “charge pump” is a small hydraulic pump that supplies oil to the main systems and helps maintain proper pressure in hydraulic circuits even when other pumps are delivering flow. Because many of these machines are still in service decades later, understanding maintenance of the charge-pump filter is important for reliability.
Common Issue: Dirty or Clogged Charge‑Pump Filter
Operators of older 580SK backhoes (such as a 1990 model) frequently raise concern over the charge-pump filter. Over time, this filter can become clogged with debris, metal slivers, or degraded seal material. A restricted charge-pump filter can lead to:

• Low charge pressure, causing cavitation or poor flow to hydraulic control valves
  
• Erratic behavior of boom, bucket, or backhoe circuits
  
• Increased wear on the main hydraulic pump due to inadequate supply
  

One real-world report describes a 580SK having very sluggish hydraulic response, especially when the operator tried to move both boom and bucket. After replacing the charge-pump filter, hydraulic performance noticeably improved, and the machine’s control became crisper.
Location and Identification of the Charge-Pump Filter
The charge-pump filter on a 1990 580SK typically sits in a small filter housing that is separate from the main hydraulic filter assembly. Key details:

• The filter housing commonly has a screw-on cover, allowing access to the filter element.
  
• The filter is relatively small — often required spare filters are modest in cost and size.
  
• Because the charge pump delivers relatively low pressure compared to the main pump, the filter is rated for lower flow but still captures fine particles.
  

Maintenance Recommendations

• Regular Inspection Interval: Check the charge-pump filter every 500 hours, or at least annually on machines in light-duty use.
  
• Replacement: Replace the filter element rather than just cleaning. Re-used elements may compress or distort.
  
• Fluid Cleanliness: Use clean, high-quality hydraulic oil (meeting Case’s OEM specifications). Contaminated hydraulic fluid contributes significantly to filter clogging.
  
• Bleeding the System: After replacing the filter, bleed any air from the charge circuit by operating the loader or backhoe functions gently to starve and then re-pressurize the system.
  
• Monitoring: Keep a service log of filter changes. If you're changing the charge-pump filter more frequently than the main hydraulic filter, inspect for sources of contamination upstream (e.g., worn hoses or plungers).
  

Preventive Tips

• Install a sight glass or magnet on the charge-pump return line (if not factory-equipped) to monitor for metal flakes.
  
• Protect the filter cover from damage — dents or warps can lead to poor sealing or leaks.
  
• Use a magnetic drain plug in the charge-pump reservoir (if possible) to capture ferrous particles before they get to the filter.
  
• If the machine is used heavily or in dirty environments, consider a filter upgrade or higher micron‑rating filter (ensuring compatibility).
  

Conclusion
For a 1990 Case 580SK, maintaining the charge‑pump filter is a key but often overlooked task. A clogged filter can degrade hydraulic performance, increase wear, and lead to more serious failures. Regular inspection, timely replacement, and clean hydraulic fluid make a big difference in how responsively the loader‑backhoe performs.