10-20-2025, 02:05 PM
Finding a 627E with a 3406 rear engine is rare but possible
Caterpillar 627E scrapers equipped with a 3406 engine in the rear are uncommon in the used equipment market. Most units were built with 3306 engines, making the 3406 configuration a niche variant often sought by contractors working in high-load or steep-grade environments.
Caterpillar 627E development and engine pairing
The 627E is part of Caterpillar’s long-running series of motor scrapers, designed for high-volume earthmoving in mining, road building, and large-scale site development. Introduced in the late 1980s, the E-series improved upon the D-series with better hydraulics, enhanced operator comfort, and more efficient load control.
Standard 627E units were powered by a front-mounted 3406 engine and a rear-mounted 3306 engine. The 3406, a 14.6-liter inline-six diesel, was known for its durability and torque, making it ideal for the front drive unit. The 3306, a smaller 10.5-liter engine, was sufficient for rear assist in most applications. However, some contractors requested dual 3406 configurations for added power in steep terrain or heavy clay.
Why dual 3406 configurations are rare
Finding a 627E with a rear 3406 engine requires targeted searching through:
One contractor in Colorado recalled using a dual-3406 627E on steep shale cuts where standard scrapers bogged down. The extra torque allowed continuous loading without stalling, saving hours per shift. However, he noted that fuel consumption increased by nearly 30%, and rear engine service required custom parts.
Another operator in Alberta found a retired unit in a gravel pit, rebuilt the rear 3406, and used it for hauling wet clay. He reported excellent performance but struggled to find replacement mounts and cooling components.
Alternative solutions and retrofit options
If a dual-3406 unit cannot be found, consider:
While rare, Caterpillar 627E scrapers with a rear-mounted 3406 engine do exist and offer superior performance in demanding conditions. Locating one requires persistence and regional knowledge, and operating such a unit demands careful maintenance and fuel planning. For contractors needing maximum power in dual-engine scrapers, the search is worth the effort.
Caterpillar 627E scrapers equipped with a 3406 engine in the rear are uncommon in the used equipment market. Most units were built with 3306 engines, making the 3406 configuration a niche variant often sought by contractors working in high-load or steep-grade environments.
Caterpillar 627E development and engine pairing
The 627E is part of Caterpillar’s long-running series of motor scrapers, designed for high-volume earthmoving in mining, road building, and large-scale site development. Introduced in the late 1980s, the E-series improved upon the D-series with better hydraulics, enhanced operator comfort, and more efficient load control.
Standard 627E units were powered by a front-mounted 3406 engine and a rear-mounted 3306 engine. The 3406, a 14.6-liter inline-six diesel, was known for its durability and torque, making it ideal for the front drive unit. The 3306, a smaller 10.5-liter engine, was sufficient for rear assist in most applications. However, some contractors requested dual 3406 configurations for added power in steep terrain or heavy clay.
Why dual 3406 configurations are rare
- Cost and weight: The 3406 is significantly heavier and more expensive than the 3306. Installing two 3406s increased machine weight and fuel consumption.
- Production volume: Caterpillar produced far fewer dual-3406 units, often as custom orders or regional variants.
- Maintenance complexity: Synchronizing two high-output engines requires precise calibration and more frequent service.
- Market preference: Most buyers opted for standard configurations to reduce operating costs and simplify logistics.
Finding a 627E with a rear 3406 engine requires targeted searching through:
- Specialized heavy equipment auctions
- Regional dealers in mining or mountain construction zones
- Private fleets with custom-built scrapers
- Verify engine serial numbers and block casting codes
- Check for frame modifications to accommodate the larger engine
- Inspect cooling systems and rear driveline for signs of stress
- Confirm that both engines are synchronized and load-sharing correctly
One contractor in Colorado recalled using a dual-3406 627E on steep shale cuts where standard scrapers bogged down. The extra torque allowed continuous loading without stalling, saving hours per shift. However, he noted that fuel consumption increased by nearly 30%, and rear engine service required custom parts.
Another operator in Alberta found a retired unit in a gravel pit, rebuilt the rear 3406, and used it for hauling wet clay. He reported excellent performance but struggled to find replacement mounts and cooling components.
Alternative solutions and retrofit options
If a dual-3406 unit cannot be found, consider:
- Retrofitting a 3406 into a 3306-equipped rear frame (requires engineering and welding)
- Upgrading the 3306 with turbo and intercooler enhancements
- Using a 627G or 627K model with electronically managed torque distribution
While rare, Caterpillar 627E scrapers with a rear-mounted 3406 engine do exist and offer superior performance in demanding conditions. Locating one requires persistence and regional knowledge, and operating such a unit demands careful maintenance and fuel planning. For contractors needing maximum power in dual-engine scrapers, the search is worth the effort.
