The Detroit Diesel Series 60 engine losing prime is a common issue that can lead to starting problems and reduced performance. This problem occurs when fuel drains from the system, requiring the engine to be primed before it can start. Let's explore the causes and solutions for this frustrating issue.

Common Causes

Faulty Check Valve

The most frequent cause of a Series 60 losing prime is a defective check valve. This valve is typically located on the back of the cylinder head, on the fuel return line. Its purpose is to prevent fuel from draining back into the tank when the engine is off. When this valve fails, fuel can leak out of the system, causing the engine to lose prime.

Damaged O-rings

Worn or damaged O-rings on fuel injectors can also lead to prime loss. These small seals prevent fuel from leaking out of the injector body. When they fail, fuel can escape the system, requiring repriming before the next start.

Air in the Fuel System

Air entering the fuel system through loose fittings, cracked lines, or a faulty fuel pump can cause the engine to lose prime. This issue can be particularly tricky to diagnose as the air leak may not be immediately visible.

Solutions and Fixes

Replace the Check Valve

If you suspect a faulty check valve:

  • Locate the valve on the back of the cylinder head
  • Remove and inspect it for debris or damage
  • Replace the valve if necessary

Inspect and Replace O-rings

To address potential O-ring issues:

  • Remove the fuel injectors
  • Inspect the O-rings for signs of wear or damage
  • Replace any compromised O-rings
  • Ensure proper installation when reassembling

Bleed the Fuel System

To remove air from the system:

  • Loosen the fuel return line at the back of the head
  • Crank the engine until fuel flows steadily without bubbles
  • Tighten the return line and attempt to start the engine

Check Fuel Lines and Fittings

Inspect all fuel lines and connections:

  • Look for cracks, loose fittings, or signs of wear
  • Tighten any loose connections
  • Replace damaged lines or fittings

Fuel Pump Inspection

If the problem persists:

  • Check the fuel pump for proper operation
  • Ensure it's delivering adequate pressure
  • Replace the pump if it's not functioning correctly

Preventive Measures

To minimize the risk of losing prime:

  • Regularly maintain your fuel system
  • Replace fuel filters at recommended intervals
  • Keep fuel tanks at least half full to reduce condensation
  • Address any fuel leaks promptly

By understanding these causes and implementing the appropriate fixes, you can significantly reduce the likelihood of your Detroit Diesel Series 60 losing prime. Regular maintenance and prompt attention to any fuel system issues will help ensure reliable starts and optimal engine performance.

FAQs About Detroit Diesel Series 60 Losing Prime

    • How often should I replace the check valve?
      Check valves should be inspected during regular maintenance and replaced if showing signs of wear or every 2-3 years as preventive maintenance.
    • Can cold weather cause prime loss?
      Yes, extreme cold can sometimes cause fuel gelling, which may mimic prime loss symptoms. Using winter-grade fuel and fuel additives can help prevent this issue.
    • Is it safe to use starting fluid when the engine loses prime?
      While starting fluid can help in emergencies, it's not recommended for regular use as it can damage engine components. Always prime the system properly instead.