Diagnosing a No-Start Condition on a Case 580B Diesel Backhoe

[MikePhua]

The Case 580B and Its Mechanical Simplicity
The Case 580B was introduced in the early 1970s as part of Case Corporation’s push to dominate the loader-backhoe market. With a naturally aspirated diesel engine, mechanical fuel injection, and straightforward electrical systems, the 580B was designed to be field-serviceable and durable. It became a favorite among municipalities, farmers, and contractors for its reliability and ease of repair.
Despite its reputation, age and long periods of inactivity can lead to stubborn no-start conditions. When a 580B sits for months or years, fuel system components may seize, electrical connections corrode, and internal pump mechanisms stick—especially in humid or contaminated environments.
Initial Checks Before Cranking
When approaching a non-starting 580B, begin with the basics:

• Fully charge the battery and verify voltage under load
  
• Inspect fuel tank for contamination or water
  
• Replace both primary and secondary fuel filters
  
• Bleed air from the fuel system by loosening bleed screws and cycling the hand primer or cranking the engine
  

The fuel system on the 580B is gravity-fed to the injection pump, passing through two filters before reaching the pump inlet. If fuel reaches the pump but fails to exit through the injector lines, the issue lies within the pump itself.
Injection Pump Behavior and Common Failures
The 580B uses a rotary-style injection pump, typically manufactured by Roosa Master or Stanadyne. These pumps rely on internal plungers to pressurize and deliver fuel to the injectors. When these plungers seize due to varnish, corrosion, or fuel degradation, the pump may receive fuel but fail to deliver it.
Key symptoms of a stuck pump:

• Fuel present at the pump inlet but absent at injector lines
  
• Return line disconnected with no fuel flow
  
• Bowl inside pump remains dry despite fuel supply
  
• Engine attempts to start only when ether is sprayed
  

To test pump internals:

• Remove the inlet fitting and fill the pump manually with clean diesel
  
• Crank the engine and observe whether the fuel level drops
  
• If fuel is drawn in, the internal rotor is turning
  
• If fuel remains static, the pump may be seized
  

A functioning metering valve is also critical. This valve regulates fuel delivery and is actuated by the manual shut-off cable. With the pump cover removed, the operator should observe movement of the shut-off cam and the metering valve arm. If the arm is stuck, it can be freed manually by gently pushing it back and forth. A free-moving metering valve is essential for fuel flow.
Advanced Troubleshooting Techniques
If basic tests fail, further steps include:

• Loosening injector line nuts at the injectors and cranking to observe fuel spurting or air bubbles
  
• Pressurizing the fuel tank with low-pressure air (3–5 psi) to assist fuel flow
  
• Checking for fog or mist at the exhaust during cranking, which indicates fuel injection
  
• Inspecting the internal filter screen at the pump inlet for blockage
  

If no fuel reaches the injectors and the metering valve is free, the pumping plungers may be seized. These components are deep within the pump and require disassembly to access. Some technicians attempt to free plungers by introducing ATF or Sea Foam into the pump and rotating the engine slowly. While this may work in mild cases, severe seizure often requires professional rebuilding.
Electrical System and Safety Interlocks
The 580B includes two neutral safety switches that prevent the starter from engaging unless the transmission is in neutral. These switches do not affect fuel delivery or pump operation. However, they should be verified if the starter fails to engage.
To test:

• Ensure gear selector is in neutral
  
• Bypass safety switch temporarily to confirm starter function
  
• Inspect wiring for corrosion or loose connections
  

If the starter cranks but the engine does not fire, the issue is mechanical or fuel-related—not electrical.
Cost of Pump Rebuild and Replacement
Rebuilding a rotary injection pump can cost between $400 and $800 depending on severity and parts availability. Common rebuild tasks include:

• Replacing plungers, seals, and gaskets
  
• Cleaning varnish and corrosion
  
• Calibrating fuel delivery rates
  
• Testing under load
  

Some rebuilders offer exchange programs or walk-through guidance for removal and shipping. Removing the pump requires careful labeling of lines and timing marks to ensure proper reinstallation.
Field Anecdotes and Practical Advice
One operator in South Carolina shared that 65% of pumps he receives have stuck plungers, and nearly half require hammer and punch removal. He cautioned against excessive disassembly without proper tools and recommended checking metering valve movement before proceeding.
Another user noted that after sitting for five years, his 580B showed no fuel at injectors despite full tank and new filters. After manually freeing the metering valve and pressurizing the tank, fuel began to flow and the engine started with minimal ether.
Conclusion
A Case 580B that won’t start after sitting idle is often suffering from fuel system stagnation. By methodically checking fuel flow, metering valve movement, and pump internals, operators can isolate the issue and determine whether a rebuild is necessary. With patience and mechanical insight, even a stubborn 580B can be brought back to life—ready to dig, lift, and earn its keep once again.