C7.1 Industrial Engine and Generator Set Engine Vibration Is Excessive Caterpillar

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

Probable Causes

• Vibration damper

• Engine supports

• Low compression (cylinder pressure)

• Electronic unit injectors

• Individual malfunctioning cylinder

Recommended Actions

Vibration Damper

Check the vibration damper for damage. If necessary, install a new vibration damper. Inspect the mounting bolts for damage and/or for wear. Replace any damaged bolts. Refer to Disassembly and Assembly, "Vibration Damper and Pulley - Remove" and Disassembly and Assembly, "Vibration Damper and Pulley - Install".

Ensure that the repairs have eliminated the fault. If the vibration is still present, proceed to "Engine Supports".

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, proceed to "Electronic Unit Injectors".

Electronic Unit Injectors

1. Use the electronic service tool to perform the automatic "Cylinder Cut Out Test". If the compression test that was performed in "Low Compression (Cylinder Pressure)" was satisfactory, any faulty injectors will be identified by the "Cylinder Cut Out Test".

2. Remove any faulty electronic unit injectors. 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, proceed to "Malfunctioning Individual Cylinder".

Malfunctioning Individual Cylinder

1. With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test". As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be a noticeable change in the sound of the engine. If a change in the sound of the engine is not noted, the isolated cylinder is not operating under normal conditions. If a change in the sound of the engine is less noticeable, the cylinder may be 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 are detected, contact the technical communicator at a Cat dealer.