Reviving a Mitsubishi BD2G Dozer After Years of Dormancy

[MikePhua]

The BD2G and Mitsubishi’s Compact Dozer Legacy
The Mitsubishi BD2G is a compact crawler dozer developed during the late 1980s and early 1990s, designed for light earthmoving, grading, and site preparation. Mitsubishi Heavy Industries, founded in 1884, has long been a key player in industrial machinery, with its construction equipment division gaining traction in Southeast Asia, North America, and Australia. The BD2 series, including the BD2F and BD2G variants, became popular for their reliability, ease of maintenance, and suitability for small contractors and landowners.
While exact global sales figures for the BD2G are hard to pin down, estimates suggest that over 10,000 units were sold across Asia and North America between 1989 and 2005. The BD2G featured a 3-liter diesel engine, hydrostatic transmission, and a 24-volt electrical system—making it a robust yet manageable machine for solo operators and small crews.
Terminology Annotation

• Hydrostatic Transmission: A drive system using hydraulic fluid to transfer power from the engine to the tracks, allowing for smooth variable-speed control.
  
• Cold Cranking Amps (CCA): A rating that indicates a battery’s ability to start an engine in cold temperatures. Higher CCA values mean better cold-start performance.
  
• Series Connection: Electrical configuration where voltage adds up across batteries, used to achieve 24 volts from two 12-volt batteries.
  

Assessing a Long-Sitting Machine
Reviving a dozer that has sat idle for 3–4 years requires a methodical approach. The first concern is whether the engine and transmission are still mechanically sound. Before investing in new batteries or fluids, it’s wise to perform a static inspection:

• Check for rodent damage to wiring and hoses.
  
• Inspect hydraulic lines for dry rot or cracking.
  
• Verify fluid levels and look for signs of contamination.
  
• Rotate the engine manually to ensure it’s not seized.
  

A common mistake is rushing to install new batteries without confirming the engine’s condition. Borrowing a pair of known-good batteries for initial testing is a cost-effective strategy. If the engine cranks freely and shows signs of life, then investing in high-quality batteries becomes worthwhile.
Choosing the Right Batteries
The BD2G’s 24-volt system requires two 12-volt batteries connected in series. Recommendations vary, but most experts suggest batteries with at least 600 CCA each. In colder climates or for machines expected to start in sub-freezing conditions, opting for 700–800 CCA per battery is prudent.
Battery setup should follow this configuration:

• Battery 1: Negative terminal to chassis ground.
  
• Battery 1 Positive to Battery 2 Negative (series jumper).
  
• Battery 2 Positive to starter and electrical system.
  

Avoid parallel connections, which would maintain 12 volts and fail to power the starter properly. Also, ensure the battery terminals are clean and tight, and use dielectric grease to prevent corrosion.
Electrical System Nuances
Japanese machines like the BD2G almost universally use negative ground systems. Positive ground setups were more common in older British and American equipment but are virtually nonexistent in post-1980 Japanese designs. Miswiring a 24-volt system can lead to blown fuses, fried alternators, or worse—so double-check polarity and terminal routing.
If the original batteries are still in place, use their configuration as a guide. Color-coded cables (red for positive, black for negative) can help, but always verify with a multimeter before connecting new batteries.
Cold Start Behavior and Engine Characteristics
The BD2G’s 3-liter diesel engine is known for its easy cold starts, provided the glow plugs are functional and fuel delivery is intact. Anecdotal reports suggest these engines can start in temperatures as low as -10°C (14°F) without block heaters, though performance improves with preheating.
In one case from northern Idaho, a BD2G was successfully started after sitting for five years using two 800 CCA batteries and a shot of ether. The engine ran rough for the first few minutes but smoothed out once the injectors cleared.
Fuel System Precautions
Before attempting a start, drain old diesel from the tank and replace fuel filters. Diesel degrades over time, forming varnish and microbial sludge that can clog injectors and damage pumps. Use fresh fuel and consider adding a biocide if contamination is suspected.
Inspect the fuel lines for brittleness and leaks. Prime the system manually if needed, and check that the lift pump is operational. If the engine fails to start, verify glow plug function and injector spray pattern.
Transmission and Hydraulic Checks
The BD2G’s hydrostatic transmission is generally resilient, but sitting idle can lead to seal shrinkage and fluid degradation. Before engaging the tracks:

• Check hydraulic fluid level and condition.
  
• Inspect for leaks around pumps and motors.
  
• Cycle the blade and ripper (if equipped) to verify hydraulic response.
  

If the machine moves sluggishly or makes whining noises, flush the hydraulic system and replace filters. Use OEM-recommended fluid or a high-quality equivalent with anti-foaming and anti-wear additives.
Revival Strategy and Cost Management
Reviving a dormant dozer can be rewarding but costly. To manage expenses:

• Start with borrowed or used batteries for testing.
  
• Prioritize engine and transmission health before cosmetic repairs.
  
• Use local salvage yards for parts like seats, hoses, and filters.
  
• Document each step to build a maintenance history.
  

A Washington-based operator once revived a BD2G for under $1,200, including batteries, fluids, and minor electrical repairs. The machine went on to serve in land-clearing projects for another six years.
Final Recommendations

• Use the highest CCA batteries that fit the compartment.
  
• Confirm 24-volt series wiring before connecting power.
  
• Replace old fuel and filters before starting.
  
• Inspect hydraulics and transmission before movement.
  
• Avoid cheap battery brands; reliability matters in remote areas.
  

Closing Reflections
Bringing a Mitsubishi BD2G back to life is more than a mechanical task—it’s a tribute to the durability of compact dozers and the ingenuity of operators. With careful planning, attention to detail, and a bit of patience, even a long-silent machine can roar again. Whether for personal use or resale, the satisfaction of revival is unmatched—and the BD2G, with its proven design and rugged simplicity, remains a worthy candidate for restoration.