Moving from one set of issues to another on my LS1 Chevy.
With the gear in 'D', A/C on and the handbrake pulled, I popped the hood and noticed for the first time that the main belt tensioner is "chattering" (video link below):
The car has had an issue with vibration for some time now. The symptoms are as follows:
- severe vibration whenever the car comes to a stop (it seems to be related to the suddenness of drop in RPM)
- at idle with the gear engaged in 'D' (~600 RPM). With the car in 'P' or 'N', engine speed is ~750 RPM and the vibration is lesser but still faintly discernible.
- the vibration is felt throughout the car body and is amplified with use of the A/C.
- I don't feel any vibration the steering wheel.
I was expecting that this was due to the failure of the vibration damper on my old crank pulley, but the issue persists even after the installation of a new crank pulley.
The vibration is felt with the car stationary in 'D', regardless of whether the A/C is turned on or off (the only thing that changes is the severity), so it would appear to be an imbalance of some sort.
Based on this forum post and the fact that the issue was present before the new crank pulley installation, I would say that crank pulley alignment is not to blame.
What could cause this behavior?
I've also put together an action plan. Comments and suggestions are welcome:
- Inspect spark plugs
- Inspect throttle plate, PCV, vacuum line
- Replace belts, assess possibility of pulley misalignment
- Inspect engine mounts
- Inspect transmission mounts