Caterpillar original 10R-1257 Diesel Fuel Injector for 3126 3126B 3126E Engine D5N D6N IT38G Excavator Replacement for 178-6342 10R-0782 new original new injector

The Caterpillar CAT 3126 HEUI diesel fuel injector 10R-1257 10R1257 is a remanufactured replacement designed for CAT 3126, 3126B and 3126E engines using the Hydraulic Electronic Unit Injector fuel system. It also cross-references 178-6342, 177-4762, 229-5928, 177-4752, 192-4010, 192-4011 and 215-5678, giving fleet operators and rebuild shops a single solution for multiple OE references within the 3126 engine family. The HEUI design combines high-pressure engine oil actuation with precise electronic solenoid control to deliver accurate fuel quantity and injection timing, which is critical for stable idle, clean combustion and consistent engine response in heavy-duty service.

Each injector is disassembled, ultrasonically cleaned and inspected before reassembly with calibrated components, restoring OE flow rate and spray pattern for balanced cylinder performance. This rebuild process supports cost-effective replacement while maintaining the durability required for 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. The injector is suited for construction equipment repair, mining equipment maintenance, truck and fleet service, agricultural machinery and diesel engine rebuild shops, as well as export distribution across North America, South America, Europe, the Middle East, Southeast Asia, Africa and Australia.

To maximize service life, use clean diesel fuel, replace the fuel filter on schedule (related 1R-0762), maintain correct oil grade and change the oil filter regularly (related 1R-1807) because the HEUI system depends on oil pressure for actuation. Inspect the injector wiring harness for corrosion or oil contamination, replace O-rings and seals (related 214-7568) when required, and check the harness connector condition (related 153-8920). After installation, verify fuel pressure, check for leaks, misfire, white or black smoke, rough idle and abnormal noise, and use professional diagnostic equipment for cylinder contribution and diagnostic code scans.