John Deere 855 Compact Tractor and the Hidden Cost of Hub Seal Failure

[MikePhua]

The Rise of the 855 in Compact Utility History
John Deere introduced the 855 compact utility tractor in the late 1980s as part of its 55 Series lineup, targeting landowners, municipalities, and small-scale contractors. Built in collaboration with Yanmar, the 855 featured a 24-horsepower liquid-cooled diesel engine, hydrostatic transmission, and four-wheel drive. Its compact frame and versatile PTO system made it ideal for mowing, tilling, snow removal, and light excavation.
By the mid-1990s, the 855 had become one of Deere’s most popular compact models, with thousands sold across North America. Its reputation for reliability and ease of maintenance helped it retain value long after production ceased. Even today, well-maintained units command strong resale prices, often exceeding $8,000 depending on condition and attachments.
Hub Seal Leaks and the Risk of Bearing Failure
One of the more serious mechanical issues that can arise in aging 855 tractors is a leaking front hub seal. This seal prevents gear oil from escaping the front axle housing and protects the wheel bearings from contamination. When the seal fails, oil loss can lead to dry bearings, increased friction, and eventual bearing collapse.
Terminology annotation:
- Hub Seal: A rubber or composite ring that prevents lubricant from leaking out of the wheel hub assembly. - Bearing Collapse: A failure mode where the rolling elements inside a bearing disintegrate due to lack of lubrication or excessive load. - Front Axle Housing: The structural casing that supports the front wheels and contains the drive gears and bearings.
Operators often notice a dark oil stain near the wheel hub or hear cracking and banging noises during operation. These sounds typically indicate that the bearing has begun to fail, and continued use can result in shaft scoring, gear damage, or even wheel detachment.
Disassembly and Inspection Strategy
Repairing a failed hub seal and bearing requires partial disassembly of the front axle. The process involves:

• Removing the wheel and hub assembly
  
• Draining the axle oil
  
• Extracting the spindle and inspecting the bearing race
  
• Replacing the seal, bearing, and any damaged shims or spacers
  

A common mistake is overlooking the condition of the inner bearing race, which may appear intact but be heat-blued or pitted. Technicians should use a micrometer to check for out-of-round wear and inspect the seal seat for scoring.
Anecdotal advice from field mechanics includes:

• Always replace both bearings and seals on the affected side to prevent uneven wear
  
• Use high-quality synthetic gear oil rated for extreme pressure (EP)
  
• Torque the hub bolts evenly to avoid warping the seal seat
  

Parts Availability and Cross-Reference Tips
While John Deere no longer manufactures the 855, parts remain available through dealers and aftermarket suppliers. The hub seal and bearing assemblies can often be cross-referenced with Yanmar components, as the front axle design shares similarities with Yanmar’s compact tractor series.
Operators sourcing parts should record:

• Seal dimensions (inner diameter, outer diameter, thickness)
  
• Bearing part numbers and load ratings
  
• Axle serial number and production year
  

Terminology annotation:
- Cross-Reference: The process of identifying equivalent parts from different manufacturers based on specifications. - EP Gear Oil: Lubricant formulated with additives to withstand high-pressure contact between gears and bearings.
Some technicians fabricate custom seal pullers using threaded rods and washers to avoid damaging the housing during removal. Others recommend freezing the new seal before installation to ease press-fit seating.
Preventative Maintenance and Long-Term Reliability
To extend the life of the hub assembly and prevent future failures:

• Inspect seals annually for signs of weeping or cracking
  
• Check axle oil level every 50 operating hours
  
• Replace gear oil every 250 hours or annually, whichever comes first
  
• Avoid high-speed travel over rough terrain, which stresses the front axle
  

Operators working in muddy or sandy environments should clean the hub area regularly to prevent abrasive particles from entering the seal lip. Installing a rubber boot or shield over the hub can offer additional protection.
Lessons from the Field
One technician shared a story of an 855 used for snow removal in upstate New York. After noticing a rhythmic clunking sound during turns, he discovered the hub seal had failed weeks earlier, and the bearing had shattered. The repair required a new spindle, hub, and gear set—totaling over $1,200 in parts and labor. Had the seal been replaced at the first sign of leakage, the cost would have been under $100.
Another operator in Oregon retrofitted his 855 with upgraded seals sourced from a marine supplier, citing better resistance to water intrusion. He also installed a magnetic drain plug to capture metal shavings and monitor bearing wear.
Conclusion
The John Deere 855 compact tractor remains a workhorse decades after its release, but like all machines, it demands attentive care. A leaking hub seal may seem minor, but left unchecked, it can cascade into costly bearing failure and axle damage. Through proactive inspection, quality parts, and field-tested repair strategies, operators can preserve the integrity of their 855 and keep it running strong for years to come. In compact equipment, small leaks often lead to big lessons.