The Caterpillar D2 is a agricultural crawler tractor manufactured by Caterpillar in Peoria, Illinois, USA from 1938 to 1957.
The Caterpillar D2 is equipped with one of two engines: a 3.6 L (221.0 cu·in) four-cylinder diesel engine or a 4.1 L (252.0 cu·in) four-cylinder diesel engine and a gear type transmission with 5 forward and 1 reverse gear.
The Cat D2 dozer used a mechanical clutches steering, 12-inch tracks, and an open operator station.
The tractor could be equipped with the following engines:
- Caterpillar. It is a 3.6 L, 3,621 cm2, (221.0 cu·in) four-cylinder natural aspirated diesel engine with 95.0 mm (3.74 in) of the cylinder bore and 127.0 mm (5 in) of the piston stroke. This engine produced 33.3 PS (24.5 kW; 32.9 HP) at 1,525 rpm of tested PTO output power.
- Caterpillar. It is a 4.1 L, 4,129 cm2, (252.0 cu·in) four-cylinder natural aspirated diesel engine. The cylinder bore is 102.0 mm (4.02 in) and the piston stroke is 127.0 mm (5 in). The compression ratio rating is 18.5:1.
Caterpillar D2 Specifications
| General Specifications | |
| Model | Caterpillar D2 |
| Length | 2,740 mm (107.9 in) |
| Width | – |
| Height | 1,460 mm (57.5 in) |
| Wheel base | – |
| Weight | 1939: 3,365 kg (7,419 lbs) 1955: 3,870 kg (8,532 lbs) |
| Fuel tank capacity | liters (0 US gal.; 0 Imp. gal) |
| Battery | |
| Cabin type | Open operator station |
| Engine | |
| Engine model | Caterpillar |
| Engine type | Four-stroke, liquid-cooled, inline |
| Cylinders | 4 |
| Fuel type | Diesel |
| Displacement | 3.6 L, 3,621 cm2, (221.0 cu·in) |
| Bore and stroke | 95.0 mm X 127.0 mm (3.74 in X 5 in) |
| Horsepower | 33.3 PS (24.5 kW; 32.9 HP) at 1,525 rpm |
| Torque | 169.5 N·m (17.3 kg·m, 124.9 ft·lb) at 1,050 rpm |
| Starter | – |
| Engine | |
| Engine model | Caterpillar |
| Engine type | Four-stroke, liquid-cooled, inline |
| Cylinders | 4 |
| Fuel type | Diesel |
| Displacement | 4.1 L, 4,129 cm2, (252.0 cu·in) |
| Bore and stroke | 102.0 mm X 127.0 mm (4.02 in X 5 in) |
| Compression ratio | 18.5:1 |
| Horsepower | – |
| Starter | Gasoline pony motor |
| Transmission and chassis | |
| Chassis | Crawler |
| Steering type | Mechanical clutches |
| Brakes | – |
| Transmission model | – |
| Transmission type | Gear type with dry disc clutch |
| Gears | 5 forward and 1 reverse |
| Speed | Forward: 8.2 kmh (5.1 mph) Reverse: 3.4 kmh (2.1 mph) |
| Tracks | |
| Size | 12-inch tracks |

Hello. My Dad has a D2 5u. He has reason to believe that the rear main seal is gone and dumping oil while its running ( possibly even leaks when not running). He is wondering what the cost comparison is between finding a diff pony motor or removing his & repairing what needs to be.
Thank you for your time & hopefully someone can point us in the right direction.