3126B Truck Engine Caterpillar


Unit Injector - Install

Usage:

3126 6PZ

Installation Procedure

Table 1
Required Tools    
Tool     Part Number     Part Description     Qty    
A     149-2955     Seal Protector     1    
B     149-2956     Seal Installer     1    
C     164-5927     Wire Brush     1    
9U-6862 Tapered Brush     1    
4C-5552 Large Bore Brush     1    
9U-6102 Reamer     1    
D     152-1057     Fuel Injector Installer     1    


NOTICE

Keep all parts clean from contaminants.

Contaminants may cause rapid wear and shortened component life.


Note: If the unit injectors are not equipped with injector deflectors, refer to Special Instruction, REHS0184, "Removal and Installation Instructions For the 3126B HEUI Injector".




    Illustration 1g00615101

  1. Install Tool (A) on the unit injector.



    Illustration 2g00615349



    Illustration 3g00620598

    (1) Backup ring

    (2) Cushion ring

    (3) O-ring


    NOTICE

    The O-ring seals and the backup rings must be installed in the correct orientation. Damaged seals will result in excessive oil consumption or excessive leakage under the valve cover. Use care to prevent nicks or damage to the seals.


  1. Use Tool (B) to install new backup rings (1), cushion ring (2), and O-ring seals (3) on the unit injector. Lubricate the O-ring seals and the backup rings on the unit injector with clean engine oil before installation.



    Illustration 4g00615360

  1. Inspect unit injector sleeve (5) in order to ensure that there is no damage to the sleeve. Inspect the bores for the unit injector and the injector seating surfaces for carbon deposits.

  1. Use Tool (C) to remove the carbon deposits from the bore for the unit injector and the injector seating surface.

    Note: Use a 9U-6102 Reamer in order to remove the heavy carbon deposits that are not removed from the bore for the unit injector tip. Use the 4C-5553 Brush with an electric drill in order to clean carbon deposits from the seat area of the unit injector sleeves. A 4C-6774 Vacuum Gun Kit is available in order to clean the loose material from the sleeve bore. Evacuate the fuel and oil from the cylinder before you install the unit injector. Use the 1U-5718 Vacuum Pump, 1U-5814 Bottle Assembly, and the 4C-4057 Tube to evacuate the fluid from the cylinder with the piston at top center.


    NOTICE

    After removing the injector, a certain amount of fuel and oil runs down the cylinder. Most of the fuel must be removed before the injector is reinstalled in order to avoid the possibility of hydraulic lock and severe engine damage when the engine is next cranked. In order to minimize the amount of fuel running into the cylinder, the fuel supply shutoff valve should be closed before injector removal.


  1. Position unit injector (4) in the cylinder head. Reconnect the plug for the wiring harness on the unit injector.



    Illustration 5g00615509

  1. Remove the rocker arm bolt and install Tool (D). Use Tool (D) to apply downward pressure on the top of the unit injector. Ensure that the unit injector is seated properly in the bore.

  1. Remove Tool (D) and install the rocker arm bolt. Tighten the rocker arm bolt to a torque of 100 ± 20 N·m (74 ± 15 lb ft).



    Illustration 6g00618046

  1. Install shoulder bolt (6) and socket head bolt (7) with the injector deflector in hold down bracket (8). Tighten shoulder bolt (6) to a torque of 6 ± 1 N·m (53 ± 9 lb in). Tighten socket head bolt (7) to a torque of 12 ± 3 N·m (106 ± 27 lb in).



    Illustration 7g00615583

  1. Install plugs (10) and (11). Install injection actuation pressure sensor (9) and tighten to a torque of 10 ± 2 N·m (88 ± 18 lb in).

End By: Install the valve mechanism cover. Refer to Disassembly and Assembly, "Valve Mechanism Cover - Remove and Install".

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