Mobark Industrial Engines and Their Role in Wood Processing

[MikePhua]

The Rise of Mobark and Its Equipment Lineage
Mobark, originally known as Morbark, was founded in 1957 in Winn, Michigan, by Norval Morey. The company began as a small sawmill equipment manufacturer and quickly expanded into wood chippers, grinders, and forestry machinery. By the 1980s, Mobark had become a recognized name in the biomass and mulch industry, producing high-capacity horizontal grinders and tub grinders powered by diesel engines ranging from 200 to over 1000 horsepower.
Mobark’s machines were often powered by industrial engines from Cummins, Caterpillar, Detroit Diesel, and John Deere. These engines were selected for their torque characteristics, serviceability, and ability to withstand the high dust and vibration environments typical of wood processing sites.
Engine Configuration and Application Demands
Mobark equipment typically uses inline or V-type diesel engines with turbocharging and intercooling. These engines drive hydraulic pumps, feed systems, and grinding drums. Key engine features include:

• High-displacement blocks for sustained torque
  
• Mechanical or electronic fuel injection systems
  
• Dual-element air filtration for dust-heavy environments
  
• Remote-mounted radiators with debris screens
  
• PTO (Power Take-Off) options for auxiliary systems
  

In one example, a Mobark 1300 tub grinder was equipped with a Caterpillar 3412 engine producing 800 hp. The machine processed up to 100 tons of green waste per hour, with the engine running at 1800 rpm under full load. Operators noted that engine reliability was critical, as downtime could cost thousands in lost production.
Common Engine Challenges in Wood Grinding
Engines in Mobark machines face unique stresses:

• Constant exposure to airborne wood dust and chips
  
• High vibration from drum rotation and feed impact
  
• Variable load conditions depending on material density
  
• Long idle periods followed by sudden full-throttle operation
  

Typical problems include:

• Clogged air filters leading to reduced airflow and overheating
  
• Fuel system contamination from poor tank maintenance
  
• Turbocharger wear due to dust ingestion
  
• Radiator blockage from wood fiber buildup
  
• Exhaust manifold cracking from thermal cycling
  

In one case from Georgia, a Mobark horizontal grinder began losing power during pine mulch production. The issue was traced to a partially collapsed intake hose and a clogged secondary air filter. Replacing both restored full engine output and reduced fuel consumption by 12%.
Maintenance Strategies and Engine Longevity
To keep Mobark engines running reliably:

• Inspect and replace air filters every 50 hours in dusty conditions
  
• Clean radiator fins daily with compressed air or water
  
• Drain and flush fuel tanks quarterly to remove sediment
  
• Monitor turbo boost pressure and exhaust temperature
  
• Use high-quality diesel with water separators
  

Recommended service intervals:

• Oil change: every 250 hours
  
• Fuel filters: every 100 hours
  
• Valve lash adjustment: every 1000 hours
  
• Turbo inspection: every 1500 hours
  
• Coolant flush: annually
  

Operators should also log engine hours and load conditions to anticipate wear. Installing a telematics system can help track performance metrics and schedule preventive maintenance.
Engine Replacement and Retrofit Considerations
When an engine fails beyond repair, replacement options include:

• Rebuilt OEM engines with warranty
  
• New crate engines from authorized dealers
  
• Engine swaps with compatible models from other brands
  

Key factors in retrofitting:

• Matching flywheel housing and PTO dimensions
  
• Ensuring hydraulic pump compatibility
  
• Adapting engine mounts and exhaust routing
  
• Reprogramming electronic control modules (ECMs)
  

In one retrofit project in Oregon, a Mobark grinder originally powered by a Detroit Diesel 8V92 was upgraded to a Cummins QSX15. The new engine offered better fuel efficiency, lower emissions, and easier diagnostics. After 2000 hours, the operator reported fewer shutdowns and smoother throttle response.
Operator Stories and Field Wisdom
In Alabama, a mulch producer used a Mobark tub grinder with a John Deere 6135 engine. After experiencing repeated overheating, the crew installed a larger radiator and added a hydraulic fan with reverse purge. The modification reduced engine temperature by 15°C and extended filter life.
In British Columbia, a biomass facility ran a Mobark horizontal grinder with a Cummins N14. The engine ran 16 hours a day during peak season. After switching to synthetic oil and upgrading the air intake system, the machine operated for three years without major engine repairs.
Conclusion
Mobark engines are the heartbeat of high-capacity wood processing machines. Whether powered by Cummins, Caterpillar, or John Deere, these engines face extreme conditions and require disciplined maintenance. With proper care, smart retrofits, and attention to airflow and fuel quality, Mobark equipment can deliver thousands of hours of reliable service. From clearing storm debris to producing premium mulch, the engine behind the grinder makes all the difference.