Astracast Impeller Lug Snap-Back or Pipe Movement

Astracast disposal emits a loud bang or clunk when turned off.

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Possible Causes

Loose impeller lugs snapping back against grinding plate, Sudden stop of motor causing pipe shift, Loose discharge pipe hitting cabinet, Air hammer in connected plumbing

How to Fix / Troubleshooting

Safety First: Turn OFF power at the breaker before inspecting under the sink.

  • Step 1 – Inspect grinding chamber: Check that impeller lugs are intact and not excessively loose or broken.
  • Step 2 – Check discharge piping: Ensure the discharge elbow and pipes are securely fastened and not striking the cabinet when the motor stops.
  • Step 3 – Add cushioning: Use rubber pads or clamps to prevent pipes from banging against surfaces.
  • Step 4 – Monitor: If the noise is minor and no damage is visible, it may be normal lug movement. If it worsens, consider replacing the unit.

Warning: Sudden new noises should always be investigated to rule out mechanical failure.

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Repair Difficulty

Very Easy 1/5
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