Resolving Hydraulic Pump Leaks on the Case 1845C Skid Steer

[MikePhua]

The Case 1845C and Its Hydraulic Legacy
The Case 1845C skid steer loader, manufactured from the late 1980s through the early 2000s, remains one of the most widely used compact loaders in North America. With over 60,000 units sold, its reputation for mechanical simplicity and rugged performance has made it a favorite among contractors, farmers, and rental fleets. Powered by a Cummins 4B diesel engine and equipped with a gear-driven hydraulic pump mounted at the rear of the machine, the 1845C delivers reliable hydraulic flow for lift, tilt, and auxiliary functions.
Identifying the Source of Hydraulic Leaks
Hydraulic leaks on the 1845C often originate from the pump body, shaft seal, or hose fittings. In one documented case, the splined hub that connects the pump shaft to the drive assembly had stripped over winter. After replacing the hub, the pump began leaking fluid—likely due to internal seal wear or misalignment during reinstallation.
Common leak points include:

• Shaft seal: Located at the front of the pump where the drive shaft enters. A worn seal allows fluid to escape under pressure.
  
• Pump body gasket: Seals the two halves of the pump housing. Age and vibration can cause this to fail.
  
• Inlet and outlet fittings: Loose or cracked fittings can leak under load.
  
• Mounting flange: If the pump is not torqued evenly, the flange may warp and compromise sealing surfaces.
  

Terminology Clarification

• Splined Hub: A toothed coupling that transmits torque from the engine to the pump shaft.
  
• Shaft Seal: A rubber or composite ring that prevents hydraulic fluid from leaking around the rotating shaft.
  
• Seal Kit: A set of replacement seals and gaskets designed for pump rebuilds.
  
• Pump Body: The main housing of the hydraulic pump, typically cast aluminum or steel.
  

Repair Strategy and Access Challenges
Accessing the hydraulic pump on the 1845C requires removal of the rear radiator shroud and careful maneuvering around the frame. Due to the pump’s compact design, standard sockets may not fit between the pump body and mounting bolts. Technicians often use crowfoot wrenches or stubby ratchets to reach fasteners.
Once removed, the pump should be inspected for:

• Shaft play or scoring
  
• Cracked housing or stripped threads
  
• Missing or degraded seals
  

If the shaft spline is intact, replacing the shaft seal alone may suffice. However, given the age of most 1845C units, a full seal kit is recommended. These kits typically cost around $120 and include:

• Shaft seal
  
• Body gasket
  
• O-rings for inlet and outlet ports
  
• Backup rings and wear washers
  

Sourcing Parts and Rebuild Kits
While local Case dealers may not stock parts for older models, several online suppliers specialize in legacy equipment. When ordering, provide the pump serial number—usually stamped on the underside of the housing. If the tag is unreadable, reference the machine’s serial number and pump location (rear-mounted beneath radiator).
Preventive Measures and Long-Term Solutions

• Replace hydraulic fluid every 500 hours to reduce seal wear
  
• Use high-quality ISO 46 or ISO 68 hydraulic oil depending on climate
  
• Inspect pump mounting bolts annually for torque and alignment
  
• Install a magnetic drain plug to monitor for internal wear
  

In Montana, one operator reported that after replacing the hub and seal kit, his 1845C ran leak-free for over two seasons. He emphasized the importance of cleaning the pump body thoroughly before reassembly and using thread sealant on all fittings.
Conclusion
Hydraulic pump leaks on the Case 1845C are a common but solvable issue. With careful disassembly, proper seal replacement, and attention to mounting alignment, operators can restore full hydraulic function and extend the life of this iconic skid steer. Whether patching a shaft seal or rebuilding the entire pump, the key lies in understanding the system’s design and respecting the machine’s mechanical heritage.