C4.4 Engines for Caterpillar Built Machines Engine Vibration Caterpillar

Note: This is not a fault in the electronic system.

Refer to Systems Operation, Testing and Adjusting for information on determining the cause of this condition.

Probable Causes

• Engine supports

• Low compression (cylinder pressure)

• Individual malfunctioning cylinder

• Electronic unit injectors

Recommended Actions

Engine Supports

1. Check for any of the following conditions:
   • Loose engine supports

   • Loose mounting brackets or broken mounting brackets

   • Loose bolts

   • Omitted bolts

2. Make all necessary repairs. Ensure that the repairs have eliminated the fault. If the vibration is still present proceed to "Low Compression (Cylinder Pressure)".

Low Compression (Cylinder Pressure)

1. Perform a compression test. Refer to Systems Operation, Testing and Adjusting, "Compression - Test ".

2. If low compression is noted on any cylinders, investigate the cause and rectify the cause.

   Possible causes of low compression are shown in the following list:

   • Loose glow plugs

   • Faulty piston

   • Faulty piston rings

   • Worn cylinder bores

   • Worn valves

   • Faulty cylinder head gasket

   • Damaged cylinder head

3. Perform all necessary repairs.

4. Ensure that the repairs have eliminated the fault.

5. If the repair does not eliminate the fault refer to "Malfunctioning Individual Cylinder".

Malfunctioning Individual Cylinder

1. With the engine speed at a fast idle, use the electronic service tool to isolate one cylinder at a time. Note if there is any reduction in engine speed. If a reduction in engine speed is not noted, the isolated cylinder is not operating under normal conditions. If the isolation of a particular cylinder results in a reduction of engine speed that is less than normal, this may indicate that the cylinder is operating below normal performance. Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.

2. If all cylinders have been checked and no faults were detected proceed to "Electronic Unit Injectors".

Electronic Unit Injectors

1. With the engine speed at a fast idle, use the electronic service tool to isolate one cylinder at a time. Note if there is any reduction in engine speed. If a reduction in engine speed is not noted, the isolated electronic unit injector is not operating under normal conditions. If the isolation of a particular cylinder results in a reduction of engine speed that is less than normal, this may indicate that the electronic unit injector is operating below normal performance.

2. Remove the electronic unit injector from the suspect cylinder. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove".

3. Install a new electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Install".

4. Repeat the test in 1. If the fault is still apparent, remove the replacement electronic unit injector and install the original electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove" and Disassembly and Assembly, "Electronic Unit Injector - Install".

5. If the fault is still apparent, repeat this test procedure from Test Step 1.