Diesel Nozzle Injector 320-0688

A: Extremely high requirements. Engine oil in the HEUI system is not only a lubricant, but also the "working fluid" and power source for the injectors. Only Caterpillar-approved engine oil meeting ECG-1 (diesel) or EDG-1 (gas engine) specifications must be used. Using substandard or inferior engine oil will lead to: 1. Oil foaming, resulting in unstable actuation pressure and inaccurate injection. 2. Sludge and carbon deposits clogging the delicate oil control channels inside the injectors. 3. Accelerated wear, shortening the lifespan of the injectors and high-pressure oil pump. Engine oil quality and replacement intervals are paramount to the health of the HEUI system.

A: Diagnosis requires the use of Caterpillar-specific diagnostic tools (such as ET). Common signs include:
1. Engine misfiring, excessive white or blue smoke, and insufficient power.
2. Abnormal actuation pressure data read by the diagnostic tool, or injector-related fault codes.
3. Perform a cylinder deactivation test (cut off the solenoid valve signal of a specific cylinder's injector) and observe whether the engine speed and exhaust smoke changes significantly.
4. Check for abnormal increases in oil consumption (internal fuel leakage).
5. At a professional repair shop, injector flow rate and leakage tests can be performed.

A: 1. Flow code matching: The flow code on the top of the new injector must match the code calibrated on the engine. Injectors with different codes cannot be used interchangeably, otherwise, it will lead to severe power imbalances between cylinders.
2. Cleaning: Before installation, ensure that the mounting holes, high-pressure oil, and fuel passages are absolutely clean.
3. Seal replacement: Replace all relevant O-rings and gaskets.
4. Oil system preparation: Before the first start after replacement, it is recommended to disconnect the fuel or injector circuit and use the starter to turn the engine for a short while to build up oil pressure and bleed air.
5. Programming: After replacement, it may be necessary to use an ET diagnostic tool to update and calibrate the ECU for injector replacement information.