Resolving Tandem Pump Leakage on the Case 1845C Skid Steer

[MikePhua]

The Case 1845C and Its Enduring Popularity
Case Construction Equipment, a division of CNH Industrial, introduced the 1845C skid steer loader in the late 1980s as an evolution of its successful 1845B model. Built in Burlington, Iowa, the 1845C quickly became one of the most widely used skid steers in North America, with over 60,000 units sold by the early 2000s. Its reputation for reliability, mechanical simplicity, and hydraulic strength made it a staple in agriculture, landscaping, and light construction.
Powered by a 51-horsepower Cummins 4B diesel engine and weighing approximately 5,800 pounds, the 1845C features a hydrostatic drive system with a tandem pump configuration. This setup allows independent control of each drive motor, enabling tight turns and responsive maneuvering. However, as these machines age, hydraulic leaks—especially around the tandem pump—become a common maintenance concern.
Understanding the Tandem Pump Configuration
The tandem pump in the 1845C consists of two gear-type hydraulic pumps mounted in series and driven directly by the engine. One pump typically powers the drive motors, while the other handles auxiliary functions such as lift and tilt.
Key components include:

• Drive pump section
  
• Auxiliary pump section
  
• Shaft seal and gasket surfaces
  
• Case drain ports
  
• Mounting flange and bolts
  

Terminology notes:

• Tandem pump: Two hydraulic pumps sharing a common drive shaft, used to deliver fluid to separate circuits.
  
• Case drain: A low-pressure return line that allows internal leakage to exit the pump housing safely.
  
• Shaft seal: A rubber or composite ring that prevents hydraulic fluid from leaking around the rotating shaft.
  

Common Leak Points and Symptoms
Leaks on top of the tandem pump often originate from:

• Worn shaft seals allowing fluid to escape around the input shaft
  
• Cracked or hardened O-rings between pump sections
  
• Loose or corroded mounting bolts compromising gasket compression
  
• Damaged case drain fittings or hoses
  

Symptoms include:

• Hydraulic fluid pooling on top of the pump housing
  
• Reduced hydraulic performance or erratic movement
  
• Visible misting or spray during operation
  
• Gradual loss of fluid from the reservoir
  

In one case from rural Alberta, a contractor noticed his 1845C was leaving small puddles beneath the engine bay after each use. Upon inspection, the tandem pump showed signs of seepage around the upper flange, and the case drain hose had split near the clamp.
Disassembly and Inspection Procedure
To address leakage, the tandem pump must be carefully removed and inspected. Recommended steps include:

• Disconnect battery and relieve hydraulic pressure
  
• Drain hydraulic fluid from the reservoir
  
• Remove engine shroud and access pump mounting bolts
  
• Label and disconnect all hydraulic lines
  
• Extract pump and inspect gasket surfaces and seals
  

Inspection checklist:

• Check shaft seal for cracking or hardening
  
• Inspect O-rings between pump sections for flattening or brittleness
  
• Examine case drain fittings for thread damage
  
• Clean gasket surfaces with solvent and lint-free cloth
  

In Georgia, a municipal crew rebuilt their tandem pump using a seal kit sourced from a hydraulic supplier. The original shaft seal had hardened and cracked, allowing fluid to escape under pressure. After replacement and reassembly, the leak was eliminated.
Seal Replacement and Reassembly Tips
Replacing seals requires precision and cleanliness. Best practices include:

• Use genuine or high-quality aftermarket seal kits rated for 3,000 psi
  
• Lubricate new seals with hydraulic fluid before installation
  
• Torque mounting bolts evenly in a crisscross pattern
  
• Replace case drain hoses with reinforced hydraulic-grade tubing
  
• Flush system before refilling to remove contaminants
  

Terminology notes:

• Crisscross torque pattern: A method of tightening bolts in alternating diagonal sequence to ensure even pressure.
  
• Hydraulic-grade tubing: Hose material rated for high-pressure fluid transfer, resistant to abrasion and swelling.
  

In New Zealand, a farm operator extended pump life by installing a magnetic inline filter upstream of the tandem pump. This captured metallic debris and reduced seal wear over time.
Preventive Maintenance and Long-Term Solutions
To prevent future leaks and extend pump life:

• Replace hydraulic fluid every 500 hours or annually
  
• Inspect case drain hoses quarterly for wear
  
• Monitor fluid temperature during heavy use (should stay below 180°F)
  
• Use anti-foaming additives to reduce cavitation
  
• Keep engine bay clean to spot leaks early
  

In Brazil, a contractor added a small inspection mirror and LED light to his 1845C’s engine bay, allowing quick visual checks of the pump area before each shift. This simple habit helped catch a minor leak before it became a major repair.
Operator Stories and Field Wisdom
In Tennessee, a retired operator shared that his 1845C had cleared brush and graded driveways for 20 years. When the tandem pump began leaking, he rebuilt it himself using a detailed diagram and a seal kit. The machine returned to full service and was later used to prepare a community garden.
In Chile, a mining crew refurbished an 1845C for tailings pond maintenance. After replacing the tandem pump seals and upgrading the hydraulic lines, the loader operated safely for another 1,500 hours without incident.
Conclusion
Leaks on top of the tandem pump in the Case 1845C are a common but manageable issue. With careful diagnosis, quality parts, and disciplined maintenance, operators can restore full hydraulic performance and extend the life of this iconic skid steer. Whether grading gravel, clearing snow, or lifting pallets, the 1845C continues to prove its worth when kept in top condition.