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Test Description

WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 4 

    If sufficient clearance exists to separate the transmission torque converter from the engine flywheel/flexplate, then further tests can be used to isolate the transmission from the engine.

  2. 5 

    An engine flywheel/flexplate that has excessive lateral runout, when combined with the mass of the transmission torque converter, can produce a disturbance.

  3. 6 

    An engine flywheel/flexplate that is loose at the engine crankshaft or that is cracked or damaged, when combined with the mass of the transmission torque converter, can produce a disturbance.

  4. 7 

    This step is designed to isolate the transmission from the engine to determine if the disturbance is related to the engine ONLY.

  5. 9 

    Re-indexing the transmission torque converter to the engine flywheel/flexplate alters the balance relationship between the torque converter and the rear of the engine.

  6. 11 

    Placing the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2 sensor onto the underside of the engine oil pan along the FRONT and the REAR edge allows for a determination to be made, which will help to narrow down the cause of the disturbance.

  7. 13 

    An engine flywheel that has excessive lateral runout, when combined with the extra mass of the clutch pressure plate and clutch driven plate, can produce a disturbance.

  8. 14 

    The clutch pressure plate and the engine flywheel are marked for proper indexing of the heavy-spot of one to the light-spot of the other. Improper indexing of the pressure plate to the flywheel can produce a disturbance.

  9. 15 

    An engine flywheel that is loose at the engine crankshaft or that is cracked, damaged and/or missing balance weights; and/or a clutch pressure plate and clutch driven plate that has loose springs, cracks, warpage, damage and/or missing balance weights - can produce a disturbance when their mass is combined.

  10. 16 

    An engine flywheel that is loose at the engine crankshaft or that is cracked, damaged and/or missing balance weights; and/or a clutch pressure plate and clutch driven plate that has loose springs, cracks, warpage, damage and/or missing balance weights - can produce a disturbance when their mass is combined.

  11. 17 

    Re-indexing the pressure plate to the engine flywheel alters the balance relationship between the pressure plate/flywheel assembly and the rear of the engine.

  12. 18 

    An engine flywheel/flexplate that is damaged, misaligned, and/or imbalanced, can produce a disturbance.

  13. 19 

    An engine crankshaft balancer that is damaged, misaligned, and/or imbalanced, can produce a disturbance.

Step Action Yes No
1 Were you sent here from the Vibration Analysis - Engine/Accessory Isolation table? Go to Step 2  Go to Vibration Analysis - Engine/Accessory Isolation 
2 Is the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2, available? Go to Step 3  Go to Vibration Diagnostic Aids 
3 Is the vehicle equipped with a manual transmission? Go to Step 11  Go to Step 4 
4 
  1. Raise and support the vehicle. Lifting and Jacking the Vehicle
  2. Remove the flywheel/flexplate-to-torque converter bolts access cover, if equipped.
  3. Determine if sufficient clearance exists to separate the transmission torque converter away from the engine flywheel/flexplate and safely secure the torque converter from accidentally engaging with the flywheel/flexplate.
Is there sufficient clearance to separate and safely secure the transmission torque converter away from the engine flywheel/flexplate?		 Go to Step 5  Go to Step 11 
5 
  1. With the flywheel/flexplate-to-torque converter access cover still removed, and with the vehicle still raised, mark the position of the transmission torque converter in relation to the engine flywheel/flexplate.
  2. Disconnect the torque converter and move it away from the flywheel/flexplate.
  3. Secure the transmission torque converter away from the engine flywheel/flexplate to avoid accidental engagement with the flywheel/flexplate.
  4. Lower the vehicle, start the engine and allow the engine to idle.
  5. Raise and support the vehicle. Lifting and Jacking the Vehicle
  6. Visually inspect the flywheel/flexplate for excessive lateral runout.
  7. Lower the vehicle.
  8. Turn OFF the ignition.
Did the flywheel/flexplate exhibit excessive lateral runout?		 Go to Step 8  Go to Step 6 
6 
  1. Raise and support the vehicle. Lifting and Jacking the Vehicle
  2. Inspect the flywheel/flexplate for the following:
    • Looseness at the engine crankshaft
    • Cracks and/or damage
    • Missing balance weights
Did the flywheel/flexplate exhibit any of the conditions listed?		 Go to Step 8  Go to Step 7 
7 
  1. With the transmission torque converter still secured away from the engine flywheel/flexplate to avoid accidental engagement with the flywheel/flexplate, lower the vehicle.
  2. Block the front wheels.
  3. Apply BOTH the service brakes and the park brake.
  4. With the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) and the EL-47955  Multi Diagnostic Interface MDI or the scan tool and the EL-38792-A  Electronic Vibration Analyzer (EVA) 2 still installed, start the engine.
  5. Place the transmission in NEUTRAL or PARK.
  6. Slowly increase the engine RPM to the level at which the disturbance is most noticeable.
  7. 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.
  8. Turn OFF the ignition.
Has the disturbance been significantly reduced or eliminated?		 Go to Step 9  Go to Step 11 
8
  1. If the flywheel/flexplate is loose at the engine crankshaft, tighten the flywheel/flexplate mounting bolts in sequence and to specification.
  2. If the flywheel/flexplate is cracked, damaged, and/or has missing balance weights, replace the damaged flywheel/flexplate.
Did you complete the tightening or replacement?		 Go to Step 20  -
9 
  1. Raise and support the vehicle. Lifting and Jacking the Vehicle
  2. Re-index the transmission torque converter to the engine flywheel/flexplate, 120 degrees from its original position.
  3. Reconnect the transmission torque converter to the engine flywheel/flexplate.
  4. Lower the vehicle.
  5. Block the front wheels.
  6. Apply BOTH the service brakes and the park brake.
  7. With the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) and the EL-47955  Multi Diagnostic Interface MDI or the scan tool and the EL-38792-A  Electronic Vibration Analyzer (EVA) 2 still installed, start the engine.
  8. Place the transmission in NEUTRAL or PARK.
  9. Slowly increase the engine RPM to the level at which the disturbance is most noticeable.
  10. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2.
  11. If the disturbance is still noticeable, re-index the torque converter again to obtain the least amount of disturbance.
Has the disturbance been significantly reduced or eliminated?		 Go to Step 20  Go to Step 10 
10 Replace the out-of-balance transmission torque converter.
Did you complete the replacement?		 Go to Step 20  -
11 
  1. Raise and support the vehicle. Lifting and Jacking the Vehicle
  2. Position the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) accelerometer or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2 sensor onto the underside of the engine oil pan, along the FRONT edge.
  3. Lower the vehicle.
  4. Block the front wheels.
  5. Apply BOTH the service brakes and the park brake.
  6. With the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) and the EL-47955  Multi Diagnostic Interface MDI or the scan tool and the EL-38792-A  Electronic Vibration Analyzer (EVA) 2, still installed, start the engine.
  7. Place the transmission in NEUTRAL or PARK.
  8. Slowly increase the engine RPM to the level at which the disturbance is most noticeable.
  9. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2 from the underside of the engine oil pan.
  10. Repeat steps 1 through 9, placing the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) accelerometer or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2 sensor onto the underside of the engine oil pan, along the REAR edge.
Is the disturbance greater along the FRONT of the engine?		 Go to Step 19  Go to Step 12 
12 Is the vehicle equipped with an automatic transmission? Go to Step 18  Go to Step 13 
13 
  1. Raise and support the vehicle. Lifting and Jacking the Vehicle
  2. Remove the flywheel inspection cover.
  3. Start the engine. Allow the engine to idle.
  4. Visually inspect the engine flywheel clutch surface for excessive lateral runout.
Does the engine flywheel clutch surface exhibit excessive lateral runout?		 Go to Step 18  Go to Step 14 
14  Inspect the clutch pressure plate to engine flywheel mounting for proper factory indexing.
Is the clutch pressure plate properly indexed to the engine flywheel?		 Go to Step 16  Go to Step 15 
15 
  1. Remove the clutch pressure plate and clutch driven plate from the engine flywheel.
  2. Inspect the engine flywheel for the following:
    • Looseness at the engine crankshaft
    • Cracks, warpage and/or damage
    • Missing balance weights
  3. Inspect the clutch pressure plate and clutch driven plate for the following:
    • Loose and/or damaged clutch driven plate damper springs
    • Loose and/or damaged clutch pressure plate diaphragm springs
    • Cracks, warpage and/or damage
    • Missing balance weights
Do any of the above conditions exist?		 Go to Step 18  Go to Step 17 
16 
  1. Remove the clutch pressure plate and clutch driven plate from the engine flywheel.
  2. Inspect the engine flywheel for the following:
    • Looseness at the engine crankshaft
    • Cracks, warpage and/or damage
    • Missing balance weights
  3. Inspect the clutch pressure plate and clutch driven plate for the following:
    • Loose and/or damaged clutch driven plate damper springs
    • Loose and/or damaged clutch pressure plate diaphragm springs
    • Cracks, warpage and/or damage
    • Missing balance weights
Do any of the above conditions exist?		 Go to Step 18  Go to Vibration Diagnostic Aids 
17  Re-index the pressure plate to the engine flywheel.
Did you complete the re-indexing?		 Go to Step 20  -
18  Replace the engine flywheel/flexplate.
Did you complete the replacement?		 Go to Step 20  -
19  Replace the engine crankshaft balancer.
Did you complete the replacement?		 Go to Step 20  -
20 Check the vehicle to determine if the disturbance is now significantly reduced or eliminated. Perform the following steps:
  1. Install or connect any components that were removed or disconnected during diagnosis.
  2. Install a scan tool into the customer's vehicle.
  3. Install the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2, if available, into the customer's vehicle; place the sensor in exactly the same location as it was originally placed in the vehicle.
  4. Block the front wheels.
  5. Apply BOTH the service brakes and the park brake.
  6. Start the engine.
  7. Place the transmission in NEUTRAL or PARK.
  8. Slowly increase the engine RPM to the level at which the disturbance was most noticeable.
  9. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2, if available.
  10. Place the transmission in DRIVE.
  11. Slowly increase the engine RPM to the level at which the disturbance was most noticeable.
  12. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A  Electronic Vibration Analyzer (EVA) 2, if available.
  13. If the disturbance has been significantly reduced or eliminated, confirm the results by placing the transmission into REVERSE, then repeat steps 11 and 12. 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 21  Go to Vibration Diagnostic Aids 
21 Perform the Vibration Analysis - Road Testing table. Vibration Analysis - Road Testing 
Is the disturbance still present?		 Go to Vibration Diagnostic Aids  System OK
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