Converting a High-Mount Turbo to Low-Mount on the John Deere 4045HF485

[MikePhua]

John Deere 4045HF485 Engine Overview
The John Deere 4045HF485 is a 4.5-liter, inline four-cylinder turbocharged diesel engine commonly used in industrial and agricultural applications. Part of the PowerTech series, this engine delivers up to 140 hp and is known for its reliability, fuel efficiency, and emissions compliance. It features a high-pressure common rail fuel system, electronic control module (ECU), and a factory-installed high-mount turbocharger.
John Deere’s PowerTech engines have been widely adopted in skid steers, telehandlers, generators, and compact construction equipment. The 4045HF485, in particular, has seen strong use in OEM installations where vertical space is available for high-mount turbo configurations.
Terminology Annotation

• High-Mount Turbo: A turbocharger positioned above the exhaust manifold, typically used to simplify plumbing and reduce heat exposure to lower components.
  
• Low-Mount Turbo: A turbocharger mounted below or beside the exhaust manifold, often used to reduce engine height or accommodate tight engine bays.
  
• Oil Drain Line: A gravity-fed return line that allows oil to flow from the turbocharger back to the engine sump.
  
• Compressor Clocking: Rotating the compressor housing to align the outlet with intake plumbing, necessary when repositioning the turbo.
  

Why Convert to a Low-Mount Configuration
In some installations, the high-mount turbo interferes with overhead clearance, cab structures, or hood designs. Converting to a low-mount turbo can:

• Reduce engine profile height by several inches
  
• Improve access to upper engine components
  
• Allow integration into tighter engine compartments
  
• Potentially improve heat management by distancing the turbo from sensitive electronics
  

However, this modification is not plug-and-play. It requires careful planning, custom fabrication, and attention to oil flow dynamics.
Key Challenges and Engineering Considerations
Flipping or relocating the turbo on the 4045HF485 involves several technical hurdles:

• Oil Drain Orientation: Turbochargers rely on gravity to drain oil. Mounting the turbo low may invert the drain port, causing oil pooling and eventual seal failure. A custom oil drain line with proper slope and unrestricted flow is essential.
  
• Exhaust Manifold Compatibility: The factory manifold is designed for a high-mount turbo. Switching to a low-mount setup may require a different manifold or adapter flange.
  
• Compressor Clocking: The intake side of the turbo must be rotated to align with the air filter and charge piping. This may require loosening the compressor housing and reorienting it.
  
• Support Brackets: A low-mount turbo will need custom brackets to support its weight and resist vibration. These must be fabricated from high-strength steel and mounted to engine block points.
  
• Heat Shielding: Relocating the turbo closer to hoses, wiring, or hydraulic lines increases the risk of heat damage. Additional shielding or rerouting may be necessary.
  

Field Anecdotes and Practical Solutions
In Oregon, a technician retrofitted a low-mount turbo on a 4045HF engine installed in a compact forestry mulcher. He fabricated a new oil drain line using braided stainless steel and routed it with a 15° downward slope to the sump. After 500 hours of operation, the system remained leak-free.
In Quebec, a contractor swapped the factory manifold for a side-exit version sourced from a marine application. This allowed the turbo to sit beside the engine, reducing hood height and improving visibility in a custom loader build.
Recommended Steps for a Successful Conversion

• Identify the turbo model and verify that it supports clocking and alternate mounting
  
• Source or fabricate a compatible exhaust manifold with low-mount flange orientation
  
• Design an oil drain system with unrestricted gravity flow and high-temperature hose
  
• Build support brackets using CAD or cardboard templates before cutting steel
  
• Test for oil leaks, vibration, and heat exposure during initial startup
  
• Monitor turbo performance and oil consumption over the first 100 hours
  

Industry Trends and OEM Adaptations
As equipment becomes more compact, manufacturers are increasingly designing engines with modular turbo configurations. Some newer John Deere engines offer both high- and low-mount options from the factory, depending on the application. Turbo suppliers like BorgWarner and Garrett now offer center-housing rotating assemblies (CHRA) with flexible mounting options and improved oil management.
In custom builds and retrofits, low-mount turbos are gaining popularity for their packaging advantages, especially in off-road vehicles, marine engines, and hybrid power units.
Conclusion
Converting a high-mount turbo to a low-mount configuration on the John Deere 4045HF485 is feasible but requires careful engineering. Oil drainage, manifold design, and mounting stability are critical to long-term reliability. With proper planning and fabrication, operators can achieve a cleaner engine layout, improved access, and better integration into tight compartments. As turbo technology evolves, flexibility in mounting will become increasingly important in both OEM and aftermarket applications.