When Cylinder One Goes Silent: Diagnosing No Compression on a Case 680E

[MikePhua]

Understanding the Heartbeat of an Engine
When an engine loses compression on any cylinder, its heartbeat falters. On a classic backhoe like the Case 680E, this can mean costly downtime and tough decisions about whether to repair, rebuild, or retire the old workhorse. Cylinder one failing to hold compression often signals deep internal wear—something that has sidelined countless machines and created plenty of stories in the shop.
Common Culprits Behind No Compression
Losing compression on cylinder one can stem from several causes:

• Blown Head Gasket — A blown head gasket can leak compression into adjacent cylinders or the cooling system. One operator famously discovered coolant bubbling out of the radiator cap while cranking.
  
• Burnt Valves — If the intake or exhaust valves can’t seal, compression escapes. Years of heat and carbon deposits often eat away at valve seats.
  
• Cracked Piston or Rings — A piston crack or broken rings mean combustion gases bypass the cylinder, leaving the engine weak and misfiring.
  
• Worn Cylinder Walls — Decades of work can leave the cylinder walls polished smooth and scored, giving the piston rings nothing to bite against.
  

Stories from the Field
Old backhoes like the Case 680E are often rescued more than once. A farmer in Nebraska once told of how his 680E lost compression on cylinder one during peak harvest. He parked it behind the barn for a season until a neighbor helped him pull the head. They found a valve with a chunk missing—classic fatigue from hard work. A local machine shop refaced the head and the old Case was back trenching within a week.
In another case, a municipal repair crew swapped a used engine from a junked 680G into their 680E to keep their fleet running while waiting for a rebuild kit that never arrived on time.
Finding and Fixing the Fault
Diagnosing no compression means pulling out the compression tester—old school but reliable. Mechanics then follow with a leak-down test, pinpointing where air escapes. If it hisses out the intake, suspect a bad intake valve. Out the exhaust? Burnt exhaust valve. Bubbles in coolant? Gasket or cracked head. Hissing from the oil filler? Rings or piston.
Repairs vary from pulling the head to full tear-downs. In some cases, owners patch what they can and run the machine “as is” if the work is light enough—one more season, one more trench.
Modern Parallels and Lessons
A 2022 story from a big contractor in Texas made headlines when an entire fleet of older backhoes was overhauled due to chronic low compression—partly due to extended oil change intervals and heavy loads beyond original design. It was a reminder that regular maintenance keeps rings sealing and valves seating, no matter how old the iron.
Wisdom for Old Iron Owners

• Keep up on valve lash adjustments and oil changes—neglect slowly kills cylinders.
  
• Run quality fuel and watch for air leaks that lean out combustion and overheat valves.
  
• Don’t ignore small signs like hard starting or a miss under load—these can be the first whispers of lost compression.
  

Summary
When cylinder one goes silent, it takes more than just wrenches to get an old Case 680E back to work—it takes practical skill, resourcefulness, and sometimes a bit of neighborly help. Stories of farmers, contractors, and town crews breathing new life into tired engines show that old machines, like old stories, have a way of hanging on long after they’re supposed to quit.