Chevrolet Trax: Vibration analysis - engine/accessory isolation

Special Tools

• CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH)
• EL-38792-A Electronic Vibration Analyzer (EVA) 2
• EL-38792-25 Inductive Pickup Timing Light
• EL-47955 Multi Diagnostic Interface MDI

For equivalent regional tools, refer to Special Tools and Equipment.

Test Description

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

5 A loose, damaged, misaligned, or defective powertrain insulator and/or bracket may create a transfer path into the passenger compartment.

6 A loose, damaged, misaligned, or defective exhaust system insulator and/or bracket may create a transfer path into the passenger compartment.

7 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

8 Non-rotating engine driven accessory component systems can no longer produce a unique disturbance.

9 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.

12 If the mark placed on the face of an engine driven accessory pulley 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.

13 A loose, damaged, misaligned, or defective engine driven accessory system insulator and/or bracket may create a transfer path into the passenger compartment.

15 Removing the engine driven accessory and bracket, or 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.

Vibration Analysis - Engine/Accessory Isolation

VIBRATION ANALYSIS - ENGINE BALANCE

Special Tools

• CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH)
• EL-38792-A Electronic Vibration Analyzer (EVA) 2
• EL-47955 Multi Diagnostic Interface MDI

For equivalent regional tools, refer to Special Tools and Equipment

Test Description

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

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.

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

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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

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

Vibration Analysis - Engine Balance

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