Perkins original 10R-1257 Diesel Fuel Injector for 3126 3126B 3126E Engine D5N D6N IT38G Excavator  original new injector

The Perkins 10R-1257 HEUI diesel fuel injector is engineered as a direct replacement for Perkins 3126, 3126B and 3126E engines fitted with the Hydraulic Electronic Unit Injector system. It cross-references 178-6342, 177-4762, 229-5928 and 177-4752, covering motor graders 120H and 135H, track-type tractors D5N and D6N, pipelayer 561N, wheel loaders 938G and 938G II, track loaders 953C and 963C, and excavator 325C used in construction, mining, fleet, truck and agricultural service.

Each remanufactured unit is ultrasonic cleaned, flow-tested and calibrated to deliver stable fuel quantity, balanced cylinder contribution, lower idle smoke and responsive engine performance under heavy load. The HEUI actuation uses engine oil pressure to atomize diesel precisely, supporting cold starts, steady idle and efficient combustion across demanding duty cycles in industrial and off-highway equipment.

For reliable installation, pair the injector with clean diesel fuel, a regular fuel filter such as 1R-0762, oil filter 1R-1807, STOR O-ring seal 214-7568 and the electronic control wiring harness 153-8920. Use professional diagnostic tools for cylinder contribution and misfire tests, and replace injectors as a matched set when balance is poor. Available as a single unit or a set of 6, with core exchange commonly required.