Nelson Valve Won't Shut Off: Clicking Noise After Top Replacement

Symptom: Valve Stays On, Clicking Sound

After replacing top half and solenoid on a Nelson valve, it won't close and makes a clicking noise.

Missing Step: Diaphragm Replacement

The diaphragm must be replaced when the top is off. Inspect the lower body for cracks or debris.

Clicking Noise Sources

• Solenoid plunger cycling (if controller sends erratic signal).
• Debris in lower body rattling with flow.
• Diaphragm fluttering at low pressure (noise stops when supply fully open).

O-Ring Placement

• Large O-ring: in solenoid thread port (top of body).
• Small O-ring: between body halves, centered under solenoid.

Test

Disconnect controller power. If clicking stops, controller is shorting. If continues, it's hydraulic (diaphragm/debris).