Case 1845C Engine Damage from Freezing and Recovery Strategy

[MikePhua]

The Case 1845C and Its Proven Workhorse Reputation
The Case 1845C skid steer loader was introduced in the late 1980s by Case Corporation, a company with roots dating back to 1842. Known for its reliability and simplicity, the 1845C became one of the most popular skid steers in North America, with tens of thousands sold across construction, agriculture, and landscaping sectors. Powered by a naturally aspirated Cummins 3.9L 4B diesel engine, it delivered around 60 horsepower and was praised for its torque, fuel efficiency, and ease of maintenance.
Its mechanical layout—chain drive, open cab options, and straightforward hydraulics—made it a favorite among owner-operators. Many units remain in service today, some with over 10,000 hours, thanks to rebuildable components and a strong aftermarket support network.
Consequences of Freezing Without Antifreeze
One of the most catastrophic oversights in diesel engine maintenance is neglecting to add antifreeze before winter. In the case of the 1845C, a mild winter led to complacency, but even brief exposure to sub-zero temperatures can cause ice expansion inside the cooling system. This expansion exerts pressure on internal components, often blowing out freeze plugs, cracking oil coolers, and damaging water pumps.
Terminology annotation:

• Freeze plug: A metal disc designed to pop out under ice pressure, protecting the engine block from cracking.
  
• Oil cooler: A heat exchanger that regulates engine oil temperature using coolant flow.
  
• Blowby tube: A vent pipe that routes combustion gases from the crankcase to the atmosphere or intake system.
  

In this case, the freeze plug was expelled, the oil cooler assembly was buckled, and the water pump was compromised. These were replaced, but the engine began expelling milky oil-water mixture from the blowby tube—indicating deeper internal contamination.
Initial Diagnosis and Fluid Behavior
Upon startup, the engine ran without unusual noises, but milky fluid poured from the lower right side. This mixture is a classic sign of coolant intrusion into the crankcase. The dipstick was coated in emulsified oil, and the radiator had drained a suspiciously thin fluid before clearing.
The most likely causes included:

• Residual water trapped in the oil pan
  
• Coolant entering through a cracked head or failed gasket
  
• Internal corrosion from prolonged exposure
  

A full drain revealed nearly 7 gallons of contaminated fluid—far exceeding the engine’s 11-quart oil capacity. This confirmed that coolant had flooded the crankcase, either during the freeze event or from a persistent leak.
Flushing and Temporary Recovery Attempts
To assess the extent of damage, a multi-step flushing procedure was attempted:

• Drain all oil and coolant
  
• Refill with cheap oil and one quart of ATF (Automatic Transmission Fluid) to aid cleaning
  
• Install a disposable oil filter
  
• Run the engine to operating temperature
  
• Drain and inspect fluid again
  

ATF contains detergents and friction modifiers that help suspend contaminants and clean internal surfaces. This method, while not a substitute for professional flushing, can reveal whether the leak is ongoing or residual.
In this case, the engine started and ran smoothly, but the next morning the radiator had emptied into the sump again—indicating an active internal breach.
Pressure Testing and Leak Confirmation
To pinpoint the leak, a low-pressure air test was performed on the cooling system. By pressurizing the radiator overflow tube and observing the oil pan drain, technicians can detect coolant migration. If water exits the pan under pressure, the breach is confirmed.
This test suggested that the leak was not just a head gasket failure but possibly a cracked cylinder head or block. The force of ice expansion had likely compromised internal castings.
Engine Removal and Inspection Strategy
With over 5,000 hours on the machine and $1,000 already spent on external repairs, the decision was made to pull the engine. The Cummins 3.9L 4B is a widely used industrial engine, found in Case backhoes, Dresser dozers, and retrofitted into Jeeps and Power Wagons. Its compact design and rebuildability make it a favorite among diesel enthusiasts.
Steps for removal included:

• Disconnecting hydraulic lines and cab mounts
  
• Removing engine mounts and lifting with a hoist
  
• Inspecting the oil pan and crankcase for cracks or corrosion
  
• Preparing to remove the cylinder head for further diagnosis
  

A shop manual was recommended to avoid timing errors or torque missteps during disassembly.
Replacement Options and Compatibility Notes
If the engine is beyond repair, replacement options include:

• Sourcing a used Cummins 4B or 4BT (turbocharged variant)
  
• Swapping heads or components from the original engine
  
• Removing the turbo if not needed for skid steer application
  

The 4BT is popular in retrofits due to its power-to-weight ratio and durability. However, compatibility with the 1845C may require adapting mounts, intake routing, and throttle linkages.
Used engines can be found through:

• Heavy equipment salvage yards
  
• Diesel rebuild shops
  
• Online marketplaces specializing in industrial power units
  

Lessons Learned and Preventative Advice
This case underscores the importance of winterizing equipment—even in mild climates. Key takeaways include:

• Always verify antifreeze concentration before freezing temperatures
  
• Drain oil immediately after suspected freeze damage
  
• Pressure test cooling systems before refilling
  
• Use ATF and cheap oil for initial flushing, but never run contaminated oil under load
  
• Consult manuals before disassembly to avoid compounding damage
  

In one anecdote from Vermont, a rebuilt Chevy 427 truck engine was destroyed by a single freeze event due to a miscommunication about antifreeze. The replacement block cost less than the rebuild, but the lesson was costly.
Conclusion
The Case 1845C remains a dependable machine, but even the toughest engines are vulnerable to ice damage. Through careful diagnosis, flushing, and inspection, operators can determine whether recovery is possible or replacement is necessary. With the widespread availability of Cummins 4B engines and a strong support network, even catastrophic failures can be overcome—provided the right steps are taken early and methodically.