Troubleshooting a 1967 Case 580CK Gas Backhoe: Electrical and Fuel System Revival

[MikePhua]

Introduction: A Classic Machine with Modern Headaches
The Case 580CK is a beloved workhorse from the 1960s, known for its rugged build and reliable hydraulics. But as with many vintage machines, age brings quirks. One owner’s experience with a 1967 gas-powered 580CK reveals how electrical gremlins and fuel delivery issues can masquerade as engine failure. This article walks through the symptoms, diagnostics, and solutions—offering practical advice for anyone restoring or maintaining an older backhoe.
Initial Symptoms and Observations

• Strong hydraulics and easy cold starts
  
• Engine runs well for a few hours, then sputters and dies
  
• Battery drains during operation
  
• Repeated stalling under load, especially when using the loader
  
• Voltage readings fluctuate but appear normal during idle
  

Electrical System Breakdown
The first suspect was the generator. After testing and confirming failure, the owner rebuilt it and replaced the voltage regulator and battery. The machine started and ran well—until it didn’t. After an hour of work, the same sputtering and power loss returned.
Key Electrical Terms
- Voltage Regulator: Controls the output of the generator or alternator to prevent overcharging
- Ballast Resistor: Reduces voltage to the ignition coil to prevent overheating
- Primary Coil Resistance: The resistance across the coil’s input terminals; affects ignition performance
- Grounding: Ensures electrical continuity between components and the chassis
Electrical Diagnostics and Solutions

• Voltage at battery during idle: ~13.45V (acceptable)
  
• Coil resistance measured at 1.4 ohms—too low without a ballast resistor
  
• No visible inline resistor found; likely removed or bypassed
  
• Positive battery terminal showed arcing; replaced terminal resolved startup issues
  
• Recommendation: Use a 3-ohm coil (e.g., NAPA Echlin 905) or install a ballast resistor to prevent coil overheating
  

Fuel System Investigation
After resolving electrical inconsistencies, attention turned to fuel delivery. The inline filter’s clear vessel showed fuel levels dropping during operation, then refilling after shutdown. This indicated a restriction or vacuum in the fuel line.
Fuel System Components and Tips
- Sediment Bowl: A glass or metal bowl that collects debris before fuel enters the carburetor
- Inline Filter: A secondary filter often added aftermarket; can restrict gravity-fed systems
- Fuel Tank Screen: Located inside the tank; filters large debris before fuel exits
Recommended Fuel System Fixes

• Remove inline filter to improve gravity flow
  
• Clean or replace sediment bowl and screen
  
• Inspect fuel tank for internal debris or clogged screen
  
• Replace fuel lines if brittle or kinked
  
• Consider pulling the tank for a full cleanout if contamination is suspected
  

Real-World Anecdote: The Super M Coil Failure
One contributor recalled a similar issue with a Super M tractor. It ran fine until the coil overheated due to lack of a ballast resistor. The engine would quit after an hour, especially in warm weather. Replacing the coil with the correct resistance solved the problem—highlighting how heat and voltage interact in older ignition systems.
Additional Parameters and Suggestions

• Charging voltage: 13.8–14.2V ideal at half throttle
  
• Coil resistance: 3 ohms without ballast, 1.5 ohms with ballast resistor
  
• Fuel flow rate: Should maintain consistent level in sediment bowl during operation
  
• Battery age: Replace if older than 5 years, especially in high-vibration environments
  
• Wiring: Inspect for splices, corrosion, and missing grounds—especially under the dash and near the coil
  

Conclusion: Layered Diagnostics for Layered Problems
The Case 580CK’s issues weren’t caused by a single failure, but a combination of aging components, missing resistors, and fuel restrictions. By methodically testing voltage, inspecting coil resistance, and observing fuel behavior, the owner narrowed down the culprits. This case underscores the importance of understanding vintage systems holistically—where electrical and fuel systems often overlap in their symptoms.
As one seasoned mechanic put it: “Old iron doesn’t lie—it just whispers. You’ve got to listen with a voltmeter and a wrench.”