Step
|
Action
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Yes
|
No
|
Refer to
Work Stall Test Warning
.
|
1
|
Were you sent here from the Vibration Analysis - Engine table?
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Go to
Step 2
|
Go to
Vibration Analysis - Engine
|
2
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Is the
EL-38792-A
Electronic Vibration Analyzer (EVA) 2 , available?
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Go to
Step 3
|
Go to
Step 5
|
3
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1.
|
Using the engine RPM and frequency data recorded for the customer's vehicle, determine the order of engine rotation to which the disturbance is related.
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2.
|
Determine the possible causes of the disturbance as it relates to a specific order of engine rotation.
|
Refer to
Engine Order Classification
.
Does the Engine Order Classification table indicate that the disturbance is of the same order as the engine firing frequency?
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Go to
Step 5
|
Go to
Step 4
|
4
|
Does the Engine Order Classification table indicate that the disturbance is likely related to engine driven accessories?
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Go to
Step 8
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Go to
Step 5
|
5
|
Inspect the powertrain mounts-engine, transmission, transfer case, and direct-mount drive axle, if equipped-and any powertrain braces for the following conditions:
•
|
Loose and/or missing fasteners
|
•
|
Cracked, dry-rotted, and/or oil-soaked insulators
|
•
|
Twisted, broken, torn, and/or collapsed insulators
|
•
|
Bent, twisted, and/or deformed brackets
|
Realign or replace powertrain mounts as indicated by the inspection.
Did you find and correct a condition?
|
Go to
Step 13
|
Go to
Step 6
|
6
|
Inspect the exhaust system components for the following:
•
|
Loose and/or missing fasteners
|
|
-
|
Joints and/or couplings:
Nuts, bolts, studs, clamps, straps
|
|
-
|
Bracket and/or insulator mounting
|
•
|
Inadequate clearance to body and/or chassis components
Inspect with the exhaust system both COLD and HOT; in NEUTRAL, FORWARD and REVERSE gears
|
•
|
Disconnected and/or missing insulators
|
•
|
Cracked, dry-rotted, and/or oil-soaked insulators
|
•
|
Stretched, twisted, broken, torn, and/or collapsed insulators
|
•
|
Bent, twisted, cracked, and/or deformed brackets
|
Repair, replace, and/or realign exhaust system components as indicated by the inspection.
Did you find and correct a condition?
|
Go to
Step 13
|
Go to
Step 7
|
7
|
Perform the Powertrain Mount Balance Procedure if available or perform the following procedure to re-bed the powertrain:
1.
|
Loosen, but do not remove, all powertrain mounts and exhaust system hangers.
|
2.
|
Ensure that the exhaust flexible coupling, if equipped, moves freely.
|
4.
|
Settle the powertrain by shifting the transmission from DRIVE to REVERSE.
|
5.
|
Place the transmission into NEUTRAL.
|
6.
|
Turn OFF the ignition.
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7.
|
Tighten all of the loosened fasteners with the powertrain in a relaxed position.
|
Did you complete the operation?
|
Go to
Step 13
|
-
|
8
|
Warning
|
Do not run the engine for longer than 60 seconds with the accessory drive belt, or belts removed. Overheating and/or damage may result.
|
|
|
|
|
1.
|
Remove the engine accessory drive belt, or belts.
|
2.
|
Block the front wheels.
|
3.
|
Apply BOTH the service brakes and the park brake.
|
4.
|
With the scan tool still installed, start the engine.
|
5.
|
Place the transmission in NEUTRAL or PARK.
|
6.
|
Increase the engine RPM to the level recorded during duplication of the disturbance.
|
7.
|
Allow the engine to idle, then place the transmission in DRIVE.
|
8.
|
Increase the engine RPM to the level recorded during duplication of the disturbance.
|
9.
|
Turn OFF the ignition.
|
10.
|
Install the engine accessory drive belt, or belts.
|
Was the disturbance significantly reduced or eliminated?
|
Go to
Step 10
|
Go to
Step 9
|
9
|
Were the characteristics of the disturbance altered but still present?
|
Go to
Step 11
|
Go to
Step 15
|
10
|
1.
|
Mark the face of the suspected accessory pulleys, including any related idler pulleys, near the outer edge with a paint mark.
|
3.
|
Block the front wheels.
|
4.
|
Apply BOTH the service brakes and the park brake.
|
5.
|
With the scan tool and the
EL-38792-A
Electronic Vibration Analyzer (EVA) 2 still installed, start the engine.
|
6.
|
Select the Smart Strobe feature on the
EL-38792-A
Electronic Vibration Analyzer (EVA) 2.
|
7.
|
Enter the recorded frequency of the disturbance as the initial frequency for strobe operation.
|
8.
|
Have an assistant place the transmission in NEUTRAL or PARK.
|
9.
|
Slowly increase the engine RPM to the level recorded during duplication of the disturbance, then maintain that speed.
|
10.
|
Using the
EL-38792-25
Inductive Pickup Timing Light , check each of the suspected accessory pulleys to determine if any of them is related to the frequency of the disturbance.
Check each of the accessory systems, both engaged and under maximum load and disengaged or under minimum load.
|
11.
|
Allow the engine to idle, then place the transmission in DRIVE.
|
12.
|
Slowly increase the engine RPM to the level recorded during duplication of the disturbance, then maintain that speed closely.
|
13.
|
Using the
EL-38792-25
Inductive Pickup Timing Light , check each of the suspected accessory pulleys to determine if any of them is related to the frequency of the disturbance.
Check each of the accessory systems, both engaged and under maximum load and disengaged or under minimum load.
|
14.
|
Turn OFF the ignition.
|
Did you identify an engine driven accessory system as being related to the frequency of the disturbance?
|
Go to
Step 11
|
Go to
Vibration Diagnostic Aids
|
11
|
Inspect the components of the engine driven accessory system for the following:
•
|
Loose and/or missing fasteners
|
|
-
|
Heat Shields, if equipped
|
|
-
|
Joints and/or couplings:
Nuts, bolts, studs, clamps, straps
|
|
-
|
Bracket and/or insulator mounting
|
•
|
Inadequate clearance to body and/or chassis components
Inspect with the accessory system both under a LOAD and NOT loaded
|
•
|
Bent or damaged pulleys
|
•
|
Disconnected and/or missing insulators
|
•
|
Cracked, dry-rotted, and/or oil-soaked component insulators
|
•
|
Stretched, twisted, broken, torn, and/or collapsed component insulators
|
•
|
Bent, twisted, cracked and/or deformed component brackets
|
Repair, replace, and/or realign the engine driven accessory system components as indicated by the inspection.
Did you find and correct a condition?
|
Go to
Step 13
|
Go to
Step 12
|
12
|
1.
|
Remove the engine driven accessory and bracket, or brackets from the engine.
|
2.
|
Thoroughly inspect the accessory bracket, or brackets, bolts/nuts/studs, and the accessory itself for signs of the following:
Bent, twisted, cracked and/or deformed conditions
|
3.
|
Replace any of the components found to exhibit any of these conditions.
|
4.
|
Reinstall the components to the engine.
|
Did you find and correct a condition?
|
Go to
Step 13
|
Go to
Step 17
|
13
|
Check the vehicle to determine if the disturbance is now significantly reduced or eliminated. Perform the following steps:
1.
|
Install a scan tool into the customer's vehicle.
|
2.
|
Install
EL-38792-A
electronic vibration analyzer (EVA) 2, if available, in the customer's car. Place the sensor in exactly the same location as it was originally placed in the customer's vehicle.
|
3.
|
Block the front wheels.
|
4.
|
Apply BOTH the service brakes and the park brake.
|
6.
|
Place the transmission in NEUTRAL or PARK.
|
7.
|
Slowly increase the engine RPM to the level at which the disturbance was most noticeable.
|
8.
|
Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the
EL-38792-A
Electronic Vibration Analyzer (EVA) 2, if available.
|
9.
|
Place the transmission in DRIVE.
|
10.
|
Slowly increase the engine RPM to the level at which the disturbance was most noticeable.
|
11.
|
Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the
EL-38792-A
Electronic Vibration Analyzer (EVA) 2, if available.
|
12.
|
If the disturbance has been significantly reduced or eliminated, confirm the results by placing the transmission into REVERSE, then repeat steps 10 and 11. Reverse-loading of the powertrain may increase or change the characteristics of the vibration.
|
Has the disturbance been significantly reduced or eliminated?
|
Go to
Step 18
|
Go to
Step 14
|
14
|
Have you investigated powertrain isolation as a possible cause of the disturbance?
|
Go to
Step 15
|
Go to
Step 5
|
15
|
Have you investigated engine driven accessories as a possible cause of the disturbance?
|
Go to
Vibration Analysis - Engine Balance
|
Go to
Step 16
|
16
|
Is the
EL-38792-A
Electronic Vibration Analyzer (EVA) 2 available?
|
Go to
Step 8
|
Go to
Vibration Diagnostic Aids
|
17
|
Replace the engine driven accessory component causing the disturbance.
Did you complete the replacement?
|
Go to
Step 18
|
-
|
18
|
1.
|
Install or connect components that were removed or disconnected during diagnosis.
|
Is the disturbance still present?
|
Go to
Step 2
|
System OK
|