- Commercial Engines with Mechanical Unit Injection:
- 3114
- 3116
- 3126
There are two types of fuel injection control linkages that are used on these engines.
 | |
| Illustration 1 | g00704229 |
Illustration of the 162-8756 Fuel Injection Control Linkage (Current Design) or the 170-7670 Fuel Injection Control Linkage (Current Design). Notice the washer on rivet (1). Notice the direction of rivet (1) . | |
The current design of the fuel injection control linkages is the 162-8756 Fuel Injection Control Linkage (for 3116 engines and 3126 engines) and the 170-7670 Fuel Injection Control Linkage (for 3114 engines). If you have a 162-8756 Fuel Injection Control Linkage or a 170-7670 Fuel Injection Control Linkage this publication is not applicable to your engine. Refer to Illustration 1.
 | |
| Illustration 2 | g00704226 |
Illustration of the 102-7459 Fuel Injection Control Linkage (Former Design) or the 4P-9048 Fuel Injection Control Linkage (Former Design). Notice there is no washer on rivet (2). Notice the direction of rivet (2) . | |
The former design of the fuel injection control linkages is the 102-7459 Fuel Injection Control Linkage (for 3116 engines and 3126 engines) and the 4P-9048 Fuel Injection Control Linkage (for 3114 engines). These fuel injection control linkages may need to be inspected. Refer to Illustration 2.
The rivet that retains the fuel injection control linkage to the governor link may become loose on some 3114, 3116, and 3126 engines with Mechanical Unit Injection (MUI). A loose rivet may result in wear of the rivet. A worn rivet may result in poor engine performance.
The following engines may have this condition:
- 3114 (S/N: 5EF; 1ZG; 6AF; 5JG)
- 3116 (S/N: 2WG; 4PG; 2SG; 4KG; 1SK; 1NJ; 5EN; 2MR)
- 3126 (S/N: 8NM; 6SR; 9ZR; 1ZJ)
This condition may have the following symptoms:
- Instability at low idle
- The engine dies at low idle.
- The engine surges under operational loads.
 | |
| Illustration 3 | g00704232 |
Rivet for the fuel injection control linkage (2) | |
The riveted joint for the fuel injection control linkage should be inspected. Refer to Special Instruction, REHS0601, "Inspection and Modification of the 102-7459 Fuel Injection Control Linkage and the 4P-9048 Fuel Injection Control Linkage " for the inspection procedure.
The inspection of the fuel injection control linkage should be performed when the valve cover is removed for service or repair.
In order to inspect the riveted joint for the fuel injection control linkage, the 128-8823 Pliers may need to be substituted with the 136-4149 Governor Pliers. Refer to "Modification of the 136-4149 Governor Pliers ".
If 180-7956 Clamp is used, the 128-9640 Injector Synchronization Fixture may need to be modified. Refer to "Modification of the 128-9640 Injector Synchronization Fixture Group".
Note: Caterpillar recommends the replacement of the complete fuel injection control linkage at the time of engine overhaul or engine reconditioning. The replacement of the complete fuel injection control linkage is recommended at high hours due to normal wear and increased clearances of the control shaft bearings.
If the 180-7956 Clamp is installed no further inspections of the control linkage is required.
Modification of the 136-4149 Governor Pliers
 | |
| Illustration 4 | g00701811 |
136-4149 Governor Pliers | |
The 128-8823 Pliers in the 128-8822 Fuel System and Governor Tool Group that are called out in Illustration (4) in Special Instruction, REHS0601 are the early 150 mm (6 inch) long pliers. Later 128-8822 Fuel System and Governor Tool Group came with pliers that are 238 mm (9.4 inch) long. The earlier 150 mm (6 inch) long 128-8823 Pliers will work for the inspection procedure that is outlined in Special Instruction, REHS0601 in all cases. The newer 238 mm (9.4 inch) long 128-8823 Pliers will work in some cases. When the newer 238 mm (9.4 inch) long 128-8823 Pliers will not work, the 136-4149 Governor Pliers can be used but the governor pliers must be modified. The 136-4149 Governor Pliers have jaws that are covered with rubber. The rubber coating should be removed on the last 10 mm (0.40 inch) of the tips in order to expose the original metal teeth. Refer to Illustration 4. This modification will not affect the original function of the pliers.
Modification of the 128-9640 Injector Synchronization Fixture Group
 | |
| Illustration 5 | g00701863 |
128-9640 Injector Synchronization Fixture Group | |
The 180-7956 Clamp may interfere with the 128-9640 Injector Synchronization Fixture Group during the synchronization procedure. The step in the tool must be lengthened by 6.5 mm (0.25 inch). This will leave 21 mm (0.83 inch) of the wide area at the rear of the base plate. The ends are now symmetrical. Refer to Illustration 5.