BOLT 3E7442 - Caterpillar

Introduction
The purpose of this instruction is to give a simple procedure for the diagnosis of engine related linear vibration problems in vehicular equipment. This instruction will provide a method for determining if the engine complies with Caterpillar allowable vibration levels. The complete troubleshooting procedure is outlined in flow chart form on page 3.Vibration complaints in vehicular equipment usually arise because of objectionable levels of vibration in the operator's compartment. Experience has shown that these vibration problems are usually not due to a defective engine but are caused by one of the following: 1. Engine mount defects due to misalignment or improper design.2. Cab mount defects due to misalignment or improper design.3. Misalignment or out-of-balance of engine driven equipment.The above defects contribute to vibrations that may appear to the operator to be caused entirely by the engine. The engine vibration troubleshooting procedure that follows has been designed to diagnose the true source of the vibration with a minimum expenditure of time and material.A vibration meter that measures displacement amplitude and frequency is needed to perform the vibration analysis described in this instruction. An IRD Model 320 or similar instrument can be used to perform these tests. Instructions for the use of the IRD Model 320 and more information on the subject of engine vibration can be found in the Service Training Meeting Guide 403, Form No. SESV1403. A photograph of an IRD Model 320 vibration meter and probe is shown below. If technical assistance in the interpretation of the test data is necessary, contact your Caterpillar Product Analyst in Service Engineering.Flow Chart For Troubleshooting Engine Vibration In Vehicular Equipment
Discussion Of Troubleshooting Procedure
The complete troubleshooting procedure outlined in the flow chart on page 3 consists of seven basic steps. 1. Fill out Engine Vibration Questionnaire (vibration meter not required).2. Repair all defects suggested by the questionnaire.3. Take in-chassis vibration data.4. Interpret the data and repair all suggested defects.5. Take in-chassis vibration data again.6. Take isolated engine vibration data.7. Determine if engine vibration complies with Caterpillar allowable levels.Each of the above steps, including completion of the data sheets and interpretation of vibration measurements, is discussed in detail in the following sections of this instruction. If the vibration problem is solved before completion of the entire troubleshooting procedure, it is not necessary to continue with the procedure.If an engine fails to comply with Caterpillar Tractor Co. allowable vibration levels in the isolated engine test, consult your Service Engineering Product Analyst for advice on repair.The engine vibration questionnaire is shown on the next page. The vibration test data sheets are shown on pages 10 and 12. Additional data sheets for the in-chassis test and isolated engine test can be obtained in pads of 50 sheets by ordering Special Instruction Form SEHS7915.Instructions For Filling Out Engine Vibration Questionnaire
The first step in the troubleshooting process is to fill out the engine vibration questionnaire. The purpose of the questionnaire is to record the history of the vibration problem and to identify possible non-engine causes of the