Case 580CK with 188D stalls under load

[MikePhua]

Summary
A 1968 Case 580CK equipped with the 188D diesel engine may lose RPM under load due to fuel delivery restrictions, injector wear, or internal pump issues. Diagnosing this requires inspecting the fuel system, checking for contamination, and evaluating injector timing and leakage.
Background on the Case 580CK and the 188D engine
The Case 580CK (Construction King) was introduced in the 1960s as one of the earliest integrated tractor-loader-backhoe (TLB) machines. It helped Case establish dominance in the compact construction equipment market, with tens of thousands of units sold across North America. The 580CK was powered by the Case 188D, a naturally aspirated four-cylinder diesel engine known for its simplicity and reliability. Rated at approximately 51 horsepower, the 188D was widely used in agricultural and construction equipment throughout the 1960s and 1970s.
Symptoms and operational behavior
Operators have reported that when driving uphill or applying load, the engine RPM drops sharply, sometimes to idle. Recovery requires clutching, revving, and re-engaging the transmission. Additionally, the machine becomes difficult to start, often idling briefly before stalling. Throttle response is delayed, and black smoke is present even at low RPM.
Fuel system inspection and common issues
The 188D uses a gravity-fed fuel system with a mechanical injection pump—typically a Roosa Master DB series. Common failure points include:

• Fuel tank contamination: Sediment or microbial growth can clog the petcock or in-tank filters. Draining the tank and inspecting with a wire probe can reveal blockages.
  
• Fuel filters and lines: Mold or debris in the primary filter or supply line can restrict flow. Replacing filters and blowing out lines is a first step.
  
• Injection pump inlet screen: A fine mesh screen under the inlet fitting may be clogged. Removing the inlet line and backing out the screen nut with a ¾" wrench allows inspection.
  

Injector wear and timing drift
Over time, injectors may lose spring tension, causing premature opening and fuel leakage into the cylinders. This leads to:

• Hard starting
  
• Black or white smoke
  
• Poor throttle response
  
• Diesel dilution in engine oil
  

Replacing injectors is relatively inexpensive—around $20 per unit—and can restore proper combustion timing. If replacement is not feasible, adjusting the injection pump timing may compensate for early injection, though this is not a long-term fix.
Diagnostic techniques
To isolate the problem:

• Fuel pressure test: Tee into the supply line near the pump and monitor pressure during load. A drop indicates supply restriction.
  
• Cylinder isolation: Loosen injector lines one at a time while idling. A cylinder that shows no RPM drop may have a faulty injector.
  
• Oil inspection: Presence of diesel in crankcase oil confirms injector leakage or pump seal failure.
  

Additional considerations

• If the engine stalls only during driving but not during stationary work, the issue may lie in the transmission or torque converter.
  
• Cold weather exacerbates fuel delivery problems due to increased viscosity and microbial growth.
  
• Additives like stiction removers may help clean injectors but are not substitutes for mechanical repair.
  

Recommendations

• Drain and inspect the fuel tank
  
• Replace fuel filters and clean inlet screen
  
• Test and replace injectors if spring pressure is compromised
  
• Monitor fuel pressure under load
  
• Change engine oil if diesel contamination is present
  

Conclusion
The Case 580CK with the 188D engine is a durable machine, but age-related fuel system degradation can cause RPM loss under load. A methodical inspection of the fuel delivery path, injector condition, and pump timing can restore performance. With proper maintenance, these machines continue to serve reliably in small-scale construction and agricultural operations.