The numbers below refer to the step numbers on the diagnostic table.
A loose, damaged, misaligned, or defective powertrain insulator and/or bracket may create a transfer path into the passenger compartment.
A loose, damaged, misaligned, or defective exhaust system insulator and/or bracket may create a transfer path into the passenger compartment.
Incorrectly seated and/or aligned powertrain components and/or exhaust system components may create a transfer path into the passenger compartment.
When loosening powertrain mounts in order to re-bed the powertrain, observe the following:
Do not loosen the mount bracket-to-engine bolts/nuts. Do not loosen the mount bracket-to-vehicle frame bolts/nuts if mount brackets are used.
Loosen the mount-to-mount bracket bolts/nuts if mount brackets are used, or loosen the mount-to-slotted holes in vehicle frame bolts/nuts if a direct-mount design is used.
Non-rotating engine driven accessory component systems can no longer produce a unique disturbance.
Non-rotating engine driven accessory components can no longer produce a unique disturbance. If a disturbance is still present, but the characteristics have been altered, it is possible that these component systems are acting as a transfer path for engine firing frequency, or a first order engine disturbance.
If a disturbance is still present, but the characteristics have NOT been altered, it is NOT likely that these component systems are acting as a transfer path for engine firing frequency, or a first order engine disturbance.
If the mark placed on the face of an engine driven accessory seems to stand still while running this test, then that accessory system is either responding to an existing frequency, such as engine firing pulses, or creating a disturbance.
A loose, damaged, misaligned, or defective engine driven accessory system insulator and/or bracket may create a transfer path into the passenger compartment.
Removing the engine driven accessory and brackets from the engine allows a thorough inspection to determine if any conditions are present that may create a transfer path into the passenger compartment.
Step | Action | Yes | No | ||||||||||||||||||||||||||||
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Caution: Refer to Work Stall Test Caution in the Preface section. | |||||||||||||||||||||||||||||||
1 | Were you sent here from the Vibration Analysis - Engine table? | Go to Step 2 | |||||||||||||||||||||||||||||
2 |
Does the Engine Order Classification table indicate that the disturbance is of the same order as the engine firing frequency? | Go to Step 4 | Go to Step 3 | ||||||||||||||||||||||||||||
3 | Does the Engine Order Classification table indicate that the disturbance is likely related to engine driven accessories? | Go to Step 9 | Go to Step 4 | ||||||||||||||||||||||||||||
Inspect the powertrain mounts for the following:
Did any of the powertrain mounts exhibit any of the conditions listed? | Go to Step 5 | Go to Step 6 | |||||||||||||||||||||||||||||
5 | Replace powertrain mounts as necessary. Refer to the following procedures:
Did you complete the replacement? | Go to Step 15 | -- | ||||||||||||||||||||||||||||
Inspect the exhaust system components for the following:
Did any of the exhaust systems components exhibit any of the conditions listed? | Go to Step 7 | Go to Step 8 | |||||||||||||||||||||||||||||
7 | Repair, replace, and/or realign exhaust system components, as necessary. Did you complete the repair, replacement, and/or realignment? | Go to Step 15 | -- | ||||||||||||||||||||||||||||
Re-bed the powertrain:
Did you complete the operation? | Go to Step 15 | -- | |||||||||||||||||||||||||||||
Notice: Do not run the engine for longer than 60 seconds with the accessory drive belt, or belts removed, or overheating and/or damage may result.
Was the disturbance significantly reduced or eliminated? | Go to Step 11 | Go to Step 10 | |||||||||||||||||||||||||||||
Were the characteristics of the disturbance altered but still present? | Go to Step 12 | Go to Step 17 | |||||||||||||||||||||||||||||
For information on the use of the EVA features, refer to Electronic Vibration Analyzer (EVA) Description and Operation . Check each of the accessory systems, both engaged and under maximum load and disengaged or under minimum load. Check each of the accessory systems, both engaged and under maximum load and disengaged or under minimum load. Did you identify an engine driven accessory system as being related to the frequency of the disturbance? | Go to Step 12 | ||||||||||||||||||||||||||||||
Inspect the components of the engine driven accessory system for the following:
Did any of the components of the engine driven accessory system exhibit any of the conditions listed? | Go to Step 14 | Go to Step 13 | |||||||||||||||||||||||||||||
Did you find and correct a condition? | Go to Step 15 | Go to Step 18 | |||||||||||||||||||||||||||||
14 | Repair, replace, and/or realign the engine driven accessory system components as necessary. Did you complete the repair, replacement, and/or realignment? | Go to Step 15 | -- | ||||||||||||||||||||||||||||
15 | Recheck the vehicle to determine if the disturbance is now significantly reduced or eliminated. Perform the following steps:
Has the disturbance been significantly reduced or eliminated? | Go to Step 19 | Go to Step 16 | ||||||||||||||||||||||||||||
16 | Have you investigated powertrain isolation as a possible cause of the disturbance? | Go to Step 17 | Go to Step 4 | ||||||||||||||||||||||||||||
17 | Have you investigated engine driven accessories as a possible cause of the disturbance? | Go to Step 9 | |||||||||||||||||||||||||||||
18 | Replace the engine driven accessory component causing the disturbance. Did you complete the replacement? | Go to Step 19 | -- | ||||||||||||||||||||||||||||
19 |
Is the disturbance still present? | Go to Step 2 | System OK |