Question:
We have a client who bought and installed 20 3/4″ Wade Rain Full Circle Bronze Sprinklers (16-WR-33) in February, and they functioned correctly. Now they no longer rotate. The client says they simply stopped rotating. The water source appears clean and free of anything that could affect the supply of water. What are the possible causes of this behavior?
Answer:
The client has Wade Rain Full Circle Bronze Sprinklers (16-WR-33) that used to rotate, and now none of the 20 heads rotate. That detail is important — when all heads stop rotating at once, the cause is often system-wide rather than individual sprinkler failure.
Below are the likely causes, ranked from most common to least:
**1. Water Pressure Dropped Slightly (Even if Flow Still Looks Normal)
These sprinklers rely on impact energy to rotate. If the pressure falls just a bit — even if the sprinklers still “look” like they’re spraying — the impact arm won’t snap back hard enough to rotate the head.
What to check
| Condition | Suggested Action |
| Pressure < ~25–35 PSI | Increase pump pressure or reduce number of sprinklers in the zone |
| Pump impeller wear or belt slip | Inspect/adjust pump |
| New leak in mainline or riser | Walk the line and listen for hissing |
Tell-tale sign: The sprinkler puffs water but the arm moves slowly or not at all.
**2. Fine Silt, Rust, or Sand in the Bearing Assembly
Even “clean” water often contains very fine mineral or iron particles that settle inside the bearing race. Bronze impact sprinklers are durable — but once the bearings dry or gum up, rotation stops.
This is extremely common 3–9 months after installation.
Fix
- Remove one head
- Rotate the bearing by hand
If it feels rough, gritty, or stiff, that’s the cause.
Solution Options
- Disassemble and flush bearings
- Soak in vinegar to remove scale
- Replace bearing/washer kit (inexpensive)
- In worst case: replace heads
**3. Calcium or Iron Scale Buildup (Especially if Well Water)
If water is high in calcium or iron, the bearing and arm pivot will slowly freeze up.
What to look for
- Orange/brown staining (iron)
- White, chalky buildup (lime)
Fix: Soak heads in:
- CLR
- Vinegar
- Phosphoric acid scale remover
Do NOT use muriatic acid — it attacks bronze.
**4. Wear or Damage to Spray Nozzles
If the nozzle orifice is worn, the jet loses shape → pressure falls at the arm → no rotation.
Check: Compare the jet shape to a new nozzle.
**5. Impact Arm Spring Fatigue
If the spring weakens, the arm may not “snap” back to create rotation.
This normally affects a few sprinklers, not all of them, but if they all came from the same box/batch, it’s possible.
**6. Winter Freeze Damage
If the field is in a freeze zone and water wasn’t completely drained, bearings crack or seize.
This is the #1 post-winter cause of uniform sprinkler failure.
**7. The “Human Factor” — Nozzle Swap or Adjustment Change
If the client changed nozzle sizes or added more sprinklers to the line since installation, the pressure distribution could have changed.
Worth asking:
- “Did anything else change in the system since February?”
Most Likely Root Cause (Based on Your Description)
Since all sprinklers stopped rotating at once and the water is “clean,” the top two suspects are:
- Pressure drop (pump wear, line leak, more sprinklers added, or valve setting changed)
- Mineral or silt buildup in the bearings over time
In my field experience, 90% or more of cases like this turn out to be one of those two.
Quick Field Diagnostic You Can Use
Take one sprinkler off and test it:
- Hook it to a hose with a pressure regulator at 30–40 PSI.
- If it rotates on the test line → pressure problem in field.
- If it does not rotate → bearing/scale issue.
This test settles it in 5 minutes.
Check back to see what the client discovered after we shared this information with him!
