Shaft Key | Sherwood 19667

Sherwood 19667 Shaft Key (Woodruff Key) | Sherwood Seawater Pump Impeller Shaft Replacement

The Sherwood #19667 is a replacement shaft key (Woodruff key) for Sherwood seawater pump impeller shafts. The shaft key locks the impeller to the drive shaft, transferring rotational drive to the impeller. Fits various Sherwood seawater pump models — confirm your specific pump model uses the 19667 shaft key in Sherwood's parts documentation before ordering.

Product Details:

• Part Number: 19667 (Sherwood)
• SKU: SHER-19667
• Manufacturer: Sherwood (Pentair)
• Type: Shaft Key — Woodruff Key
• Application: Sherwood seawater pump impeller shafts (various models)
• Condition: New

Additional Information

What the Shaft Key Does — Impeller Drive Coupling:

The Woodruff key is a small semicircular steel key that seats in a matching keyway slot machined into both the pump drive shaft and the impeller hub. When the impeller is pressed onto the shaft, the key engages both keyways simultaneously, creating a positive rotational lock between the shaft and impeller. Without the key — or with a sheared or missing key — the shaft spins freely inside the impeller hub and the impeller does not rotate. The result is immediate and complete loss of raw water flow through the cooling system: the engine overheats rapidly.

When to Replace the Shaft Key:

The shaft key should be inspected and replaced whenever the impeller is removed for service. Common reasons the key requires replacement:

• Sheared key — the key shears under shock load (hard start, sudden RPM change, impeller seized by debris or run-dry) and the impeller stops rotating while the shaft continues; the engine overheats and the failure mode is typically a sudden temperature spike
• Lost at disassembly — Woodruff keys are small and easily lost during impeller removal; always have a replacement on hand before beginning impeller service
• Worn or damaged keyway — a worn key allows slight rotational slip between shaft and impeller; impeller output is reduced and keyway wear in the shaft or impeller hub accelerates
• Preventive replacement — replacing the key at each impeller service is low-cost insurance at $10.95; the alternative is a sheared key during operation and an overheating engine

Impeller Service — Key Replacement as Standard Practice:

Sherwood recommends replacing the impeller at regular service intervals (typically annually or per the engine manufacturer's recommendation). Whenever the impeller is replaced, inspect the shaft key and replace it if there is any doubt about its condition. A new impeller installed on a worn or damaged key will not transfer full drive torque and the impeller service life will be shortened.

Confirm Pump Model Fitment:

The 19667 shaft key fits various Sherwood seawater pump models. Confirm your specific pump model uses the 19667 key by cross-referencing Sherwood's parts breakdown for your pump. Sherwood pump model numbers are typically stamped or labeled on the pump body. If you need assistance identifying your pump model or confirming the correct shaft key, contact us at MacombMarineParts.com with your pump model number or the engine make, model, and year.

Installation Notes:

• Confirm your pump model uses the 19667 shaft key before ordering
• Inspect the keyway slots in the shaft and impeller hub for wear or damage before installing a new key
• Seat the key fully in the shaft keyway before pressing the impeller onto the shaft
• Do not operate the seawater pump without the shaft key installed — the impeller will not rotate and the engine will overheat immediately
• Replace the shaft key whenever the impeller is removed for service as a standard practice

Frequently Asked Questions

1. What happens if the shaft key is missing or sheared?
The impeller stops rotating while the shaft spins freely inside the hub. Raw water flow through the cooling system stops immediately. The engine overheats rapidly. A sheared key typically presents as a sudden, unexplained temperature spike during operation.

2. When should I replace the shaft key?
At every impeller service. The key is inexpensive and small enough to lose during disassembly — always replace it when replacing the impeller rather than risk a sheared or missing key causing an overheat event.

3. What is a Woodruff key?
A Woodruff key is a semicircular key that fits into a matching slot (keyway) in both the shaft and the hub being driven. It creates a positive rotational lock between the two components without requiring the hub to be keyed or pinned axially.

4. How do I find my Sherwood pump model number?
The pump model number is typically stamped or labeled on the pump body or end plate. Contact us at MacombMarineParts.com with your pump model number or engine make, model, and year and we will confirm the correct shaft key for your application.

5. Can a worn keyway cause pump problems even if the key is intact?
Yes — a worn keyway in the shaft or impeller hub allows slight rotational slip even with the key in place. The impeller does not keep pace with the shaft under load, raw water output is reduced, and the keyway wear accelerates until the key shears or the impeller spins freely.