Drive Belt Rumbling and Vibration Diagnosis
Drive Belt Rumbling and Vibration Diagnosis
Drive Belt Rumbling Diagnosis
Diagnostic Aids
Vibration from the engine operating may cause a body component or another part of the vehicle to produce a rumbling noise.
The drive belts may have a condition that can not be seen or felt. Sometimes replacing the drive belts may be the only repair for the symptom.
If after replacing the drive belts and completing the diagnostic table, the noise is only heard with the drive belts installed, there might be an accessory drive component inoperative. Varying the load on the accessory drive components may aid in identifying which accessory drive component is causing the rumbling noise.
Test Description
The numbers below refer to the steps in the diagnostic table.
2. This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom.
3. This test is to verify that the drive belts are causing the rumbling. Rumbling may be confused with an internal engine noise due to the similarity in the description. Remove only one drive belt at a time if the vehicle has multiple drive belts. Operate the engine for a few seconds, this will verify if the rumbling noise is related to the drive belts or not. With the drive belts removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belts removed.
4. Inspect the drive belts to ensure that the drive belts are not the cause of the noise. Small cracks across the ribs of the drive belts will not cause the noise. Belt separation is identified by the plies of the belt separating, this may be seen at the edge of the belt or felt as a lump in the belt.
5. Small amounts of pilling is a normal condition and acceptable. When the pilling is extreme the drive belts does not have a smooth surface for correct operation.
Drive Belt Vibration Diagnosis
Diagnostic Aids
The accessory drive components may have an affect on engine vibration. An overcharged air conditioning (A/C) system, a power steering system restriction, or the incorrect fluid, or an extra load placed on the alternator are suggested items to inspect. To help identify an intermittent or an incorrect condition, vary the loads on the accessory drive components.
Test Description
The numbers below refer to the steps in the diagnostic table.
2. This test is to verify that the vibration is present during diagnosing. Other vehicle components may cause a similar symptom such as the exhaust system or the drivetrain.
3. This test is to verify that the drive belts or accessory drive components may be causing the vibration. Remove the drive belts and operate the engine for a few seconds, this will verify if the vibration is related to the drive belts or not. With the drive belts removed the water pump will not operate and the engine may overheat. Also diagnostic trouble codes (DTCs) may set when the engine is operated with the drive belts removed.
4. The drive belts may cause a vibration. While the drive belts are removed this is the best time to inspect the condition of the drive belts.
6. Inspection of the fasteners can address the possibility that a incorrect bolt, nut, spacer, or washer was installed.
9. Inspect the water pump drive shaft for being bent. Also inspect the water pump bearings for smooth operation and above acceptable play. Compare the water pump with a known, good water pump.
10. Accessory drive component brackets that are bent, cracked, or loose may put an extra strain on that accessory component causing it to vibrate.
