- On-Highway Engines:
- C-10 (S/N: 3CS1-UP; 8YS1-UP)
- C-12 (S/N: 2KS1-UP; 8YF1-UP; 9NS1-UP)
Introduction
Do not perform any procedure in this Special Instruction until you read this information and you understand this information. This Special Instruction is intended to provide a simple procedure for diagnosing cracks in the flywheel housing in truck engine applications. Also, this instruction covers the flywheel housing loose/broken bolt failures on truck engine applications. However, this procedure can be used in other applications. Experience has shown that these failures are not usually caused by a defect in the engine or a defect in the material of the flywheel and/or workmanship, but the failures are due to one of the following:
- Defects of the engine mounts due to misalignment or an improper design
- A truck that is being used improperly
- Equipment that is driven by the engine is misaligned or out-of-balance.
- Insufficient rear support of transmission overhung weight.
The above defects can contribute to the flywheel housing and/or the bolt failures that may appear to be caused entirely by the engine. This troubleshooting procedure has been designed to diagnose the true source of the failure with a minimum unnecessary expenditure of time and material. Use the following steps in the initial troubleshooting of these problems.
Vibration
If there is a vibration, please refer to Special Instruction, SEHS7914, "Troubleshooting Engine Vibration In Vehicular Equipment" and Special Instruction, REHS3291, "Troubleshooting Engine Vibration".
Vibration Questionnaire
Complete the vibration questionnaire. Refer to Special Instruction, SEHS7914, "Troubleshooting Engine Vibration In Vehicular Equipment". After completion of the questionnaire, if the following conditions exist the engine is not the cause of the vibration.
- Vehicle is in motion.
- Engine is under load.
At this point, the engine troubleshooting is complete. The customer will be responsible for any further investigation. The customer has the option of taking the unit to the OEM dealer for further investigation.
Engine
If the engine is the source of the vibration, Refer to Special Instruction, SEHS7914, "Troubleshooting Engine Vibration In Vehicular Equipment" and Special Instruction, REHS3291, "Troubleshooting Engine Vibration". These instructions will have the next steps that need to be made for your engine. This also includes an isolated engine vibration test.
Note: If the failure is on an engine with low hours, there is a possibility of a defect. Please consult your Caterpillar Dealer.