Water Contamination in Engine Oil on the Case 850B Dozer

[MikePhua]

Case 850B Dozer Background
The Case 850B is a mid-sized crawler dozer developed by Case Corporation, a company with roots dating back to 1842. Known for its rugged design and reliability, the 850B was widely used in road building, land clearing, and utility trenching throughout the 1980s and 1990s. It typically features a 6-cylinder diesel engine, hydrostatic transmission, and a blade width of around 8 feet. Case sold thousands of these units globally, and many remain in service today due to their mechanical simplicity and ease of repair.
Symptoms of Water in Engine Oil
One of the most alarming issues for any diesel engine is the presence of water in the crankcase. In the Case 850B, this manifests as:

• Milky or frothy oil expelled from the oil fill tube
  
• Overfilled crankcase with a mix of coolant and oil
  
• Steam emissions from the engine compartment
  
• Rapid coolant loss without external leaks
  

These symptoms suggest a breach between the cooling and lubrication systems, which can lead to bearing failure, piston scoring, and eventual engine seizure if not addressed promptly.
Common Causes of Internal Coolant Leaks
In older diesel engines like the one in the 850B, the most likely culprits include:

• Cylinder sleeve seal failure: The engine uses wet sleeves sealed by O-rings. Over time, these rubber seals degrade, allowing coolant to enter the crankcase.
  
• Cracked cylinder sleeves: Corrosion or cavitation can cause pinholes or fractures in the sleeve wall.
  
• Pitted block surfaces: The area where the sleeve O-rings seat may become pitted, compromising the seal.
  
• Failed head gasket or warped head: Though less likely if no combustion symptoms are present, this remains a possibility.
  

In one documented case, a contractor in Michigan discovered wormhole corrosion in a sleeve that had gone unnoticed during routine maintenance. The leak only became apparent during cold weather when thermal contraction widened the breach.
Disassembly and Inspection Strategy
To confirm the source of the leak, technicians often:

• Pressurize the cooling system with the oil pan removed to observe coolant dripping from the sleeve base or block.
  
• Remove the oil pan in-frame if possible. On the 850B, this requires sliding the pan forward under the crossmember, though clearance is tight due to the oil pump and balancer assembly.
  
• Inspect sleeves and O-rings for signs of wear, cracks, or rot.
  
• Check block surface for pitting or erosion around the sleeve seat.
  

If multiple sleeves are compromised, a full engine overhaul may be warranted. Otherwise, targeted replacement of affected sleeves and seals can restore function.
Tools and Techniques for Sleeve Removal
While commercial sleeve pullers are available, many operators use improvised methods:

• Hammer and blunt rod: Drive the sleeve upward from the bottom, taking care not to damage the block.
  
• Homemade pullers: Fabricated from steel plate and threaded rod, these tools apply upward force evenly.
  
• Heat and lubrication: Applying heat to the block and penetrating oil around the sleeve can ease removal.
  

In a 2022 rebuild, a farmer in Arkansas used a homemade puller fashioned from scrap metal and successfully removed all six sleeves without damaging the block, saving over $500 in tool costs.
Preventive Measures and Long-Term Solutions
To avoid recurrence:

• Use high-quality coolant with corrosion inhibitors.
  
• Flush cooling system annually to remove sediment and scale.
  
• Monitor oil condition regularly for signs of contamination.
  
• Replace sleeve O-rings during major service intervals, even if no leak is present.
  

If the block is pitted, options include:

• Sleeve seat machining: Resurface the block to restore a smooth sealing surface.
  
• Epoxy repair compounds: Used in low-pressure areas to fill pits, though not a permanent fix.
  
• Block replacement or remanufactured short block: Costly but effective for severely damaged engines.
  

Conclusion
Water in the engine oil of a Case 850B is a serious issue, often linked to sleeve seal failure or internal corrosion. With methodical diagnosis and careful disassembly, the root cause can be identified and repaired. These dozers, built with robust mechanical systems, reward patient and thorough maintenance with years of continued service—even when repairs must be done on a gravel floor in an unheated barn. Investing in the repair of a trusted machine often proves more economical than replacement, especially when the operator knows every bolt and bearing by heart.