Usage:
3116 (2CW1436-Up),
3126 (1WM26499-Up, 4ES455-Up, 8HW434-Up, 7LZ1613-Up) HEUI Truck Engines
The lower O-ring seal has been removed from the HEUI fuel injector groups in these truck engines. See the illustration. Tests indicate this O-ring seal is not an effective seal after a few hours of operation. This seal can take up a portion of the clamping force when the injector in installed in the cylinder head. When the seal deteriorates, this could lessen the clamping force holding the injector in position.
Location of the O-ring seal to be removed from the HEUI fuel injector group.
Until all HEUI injectors with the lower O-ring seal are depleted from inventory, it is suggested that the lower O-ring seal be removed when installing a new or remanufactured HEUI injector in the engine.
The area that seals the combustion gas from the fuel is the area of metal to metal contact between the injector cone and the sleeve. It is recommended that the sleeve be reamed whenever a HEUI injector is removed.
To confirm that a good seal exists between the HEUI injector and sleeve, use a 2P-8278 Air Fuel Tube Assembly (Plastic Sight Glass) in the fuel return to tank line after the injector installation. Use the sight glass while the engine is running to determine if there is combustion gas leakage. A steady stream of small (pencil point size) bubbles, or one pea sized bubble every 2 to 3 seconds is acceptable.