CAT 258-8745 HEUI Injector – The Durable Service Solution for C7 & C9 Medium-Duty Diesel Engines
1. Product: 258-8745
2. Compatible Equipment: Diesel Fuel Injection Systems
3. Manufacturer: Aftermarket OEM Replacement
4. Condition: Brand New, Fully Tested
5. Origin: ABOSEDE Diesel
6. Shipping period: 3-5 business days
7. Payment terms: T/T, Western Union, PayPal
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Product Introduction
The CAT 258-8745 is a HEUI (Hydraulically actuated Electronically controlled Unit Injector) engineered for the demanding duty cycles of C7 and C9 engines in vocational trucking, emergency response, and off-highway equipment. This injector delivers a maximum injection pressure of 1,500 bar (21,750 psi) with a static flow of 215 mm³/stroke at 1,400 rpm, a specification that matches the performance of the 10R-1265 while incorporating material upgrades that extend the service interval in high-idle applications. The defining feature of the 258-8745 is its hard-chrome plunger – a 15 µm coating that provides a surface hardness of 1,000 HV and a coefficient of friction of 0.10–0.12, significantly reducing the wear rate in applications where the engine idles for extended periods. This material choice, combined with a revised intensifier piston geometry, provides a service life of 6,000–8,000 hours – approximately 1,000 hours longer than the 10R-1265 in comparable duty cycles.
█ Application Coverage – C7 & C9 Engine Platforms
The 258-8745 is the factory-specified service injector for the following Caterpillar engine applications:
C7 Engine – All serial numbers, including vocational, generator, and marine configurations
C9 Engine – All ratings, including high-output variants up to 350 hp
Industrial Power Units – C7/C9 in generator sets, pumps, and compressors
Vocational Applications – Refuse, dump, mixer, fire apparatus, and emergency vehicles
The injector's 8-hole nozzle features 0.265 mm diameter orifices and a 147° spray angle, providing a droplet SMD of approximately 22 µm. It directly replaces CAT part numbers 10R-1265, 10R-1266, 0R-9803, and 236-4072 across all C7 and C9 serial numbers.
▐ Technical Specifications – Electrical and Hydraulic Data
| Parameter | Specification |
|---|---|
| Maximum Injection Pressure | 1,500 bar (21,750 psi) |
| Actuation Oil Pressure Range | 380 – 2,050 psi |
| Intensifier Ratio | 6.3:1 |
| Fuel Delivery @ 1,400 rpm | 215 mm³/stroke |
| Fuel Delivery @ 1,800 rpm | 198 mm³/stroke |
| Solenoid Coil Resistance (20°C) | 0.90 – 1.05 Ω |
| Peak Pull-in Current | 22 A |
| Nozzle Holes / Diameter | 8 × 0.265 mm |
| Spray Angle | 147° |
| Needle Lift | 0.23 mm |
| Hydraulic Opening Pressure | 270 bar |
| Leak-off Rate (new, idle) | ≤ 20 ml/min |
| Max. Engine Speed | 2,800 rpm |
| Solenoid Inductance | 2.1 mH |
| Service Life (2 µm filtration) | 6,000–8,000 hrs |
◆ Construction Details – Material Upgrades for Extended Durability
→ Hard-Chrome Plunger: The 15 µm hard-chrome plating provides a hardness of 1,000 HV – 30% harder than the nitrided surface used in some earlier HEUI injectors – and significantly reduces frictional wear in high-idle applications.
→ Carbon-Fibre-Reinforced Actuation Oil Seal: The Teflon seal includes 20% carbon fibre reinforcement, providing creep resistance at actuation oil temperatures up to 130°C.
→ Balanced Armature: The solenoid armature is dynamically balanced to minimise vibration at high frequencies, reducing armature bushing wear.