Impeller Kit | Sierra 18-3046

Sierra 18-3046 Water Pump Impeller Kit | 12-Blade | 2-7/16" Dia. | Crusader, Westerbeke, Volvo Penta, OMC, Onan, PCM

The Sierra #18-3046 is a 12-blade water pump impeller kit with gaskets for inboard and I/O marine engines. 2-7/16" diameter, 1-1/4" width. Broad cross-reference coverage across Crusader, Westerbeke, OMC/Johnson/Evinrude, Onan, Pleasurecraft Marine (PCM), and Volvo Penta applications. Supersedes Sierra 18-3060.

Part Details:

• Part Number: 18-3046 (Sierra)
• SKU: SIERRA-18-3046
• Manufacturer: Sierra
• Type: Water Pump Impeller Kit
• Blades: 12
• Diameter: 2-7/16 in.
• Width: 1-1/4 in.
• Kit Includes: Impeller and gaskets
• Supersedes: Sierra 18-3060
• Condition: New

Cross-Reference — Replaces:

• Crusader: 1003026
• Westerbeke: 11418, 11907, 33104
• OMC / Johnson / Evinrude: 3854286
• Onan: 132-0317
• Pleasurecraft Marine (PCM): R061015
• Volvo Penta: 3854286
• Sierra: 18-3060 (superseded)

Additional Information

Multi-Brand Application — One Impeller Kit:

The Sierra 18-3046 covers a wide range of inboard and I/O engine water pump applications across six OEM brands. The shared OMC/Volvo Penta part number (3854286) reflects the use of common raw water pump designs across multiple engine platforms — a single impeller specification serves the Volvo Penta, OMC/Johnson/Evinrude, and several other OEM water pump housings of the same design. Confirm by cross-referencing the OEM part number from your engine's existing impeller or water pump documentation.

12-Blade Impeller — Design and Performance:

The 12-blade configuration provides higher flow capacity compared to lower blade-count impellers of the same diameter, delivering more consistent cooling water volume at lower RPM — particularly beneficial for inboard and I/O engines that operate at sustained load in varying conditions. The neoprene impeller blades flex to create suction and push water through the raw water cooling circuit; blade flexibility and condition directly determine pump performance.

Kit Includes Gaskets:

The 18-3046 kit includes the gaskets required for the water pump housing. Replace all gaskets included in the kit at every impeller service — do not reuse old gaskets. Old gaskets that appear intact can leak after reassembly due to compression set.

Water Pump Impeller Service Intervals:

Sierra and most engine OEMs recommend replacing the raw water pump impeller annually or every 100 hours, whichever comes first. Impeller blades harden and crack over time, especially in engines that sit out of the water between uses. A failed impeller causes loss of raw water flow through the cooling system, leading to rapid engine overheating. Running dry even briefly — such as during a water start or priming — can destroy neoprene impeller blades. Signs of impeller failure include:

• Engine overheating or rising temperature under load
• Reduced or absent water flow from the tell-tale (pee hole) on outboards
• Pieces of impeller blade material in the raw water circuit or strainer
• Impeller blades taking a set (permanently bent) rather than springing back when removed

Inspect the Raw Water Circuit During Impeller Service:

When replacing the impeller, flush and inspect the raw water circuit for impeller blade fragments. Failed impeller blades can lodge in the thermostat housing, heat exchanger, exhaust manifold water passages, or raw water strainer, blocking cooling flow even after the impeller is replaced. If blade fragments are found, flush the entire raw water side of the cooling system before reassembly.

Installation Notes:

• Confirm impeller dimensions and cross-reference match your engine's water pump before ordering
• Lubricate the impeller with dish soap or glycerin before installation — do not use petroleum-based lubricant, which degrades neoprene
• Install impeller with blade curve in the correct rotational direction — refer to service documentation for your pump
• Replace all gaskets included in the kit — do not reuse old gaskets
• Check for and remove any old impeller blade fragments from the raw water circuit before reassembly
• Run engine and confirm cooling water flow from tell-tale or heat exchanger outlet after installation

Frequently Asked Questions

1. What engines does the Sierra 18-3046 fit?
The 18-3046 covers Crusader (1003026), Westerbeke (11418, 11907, 33104), OMC/Johnson/Evinrude (3854286), Onan (132-0317), Pleasurecraft Marine/PCM (R061015), and Volvo Penta (3854286) water pump applications. Confirm by cross-referencing the OEM part number from your existing impeller or water pump housing documentation.

2. What is the difference between this kit and the Sierra 18-3060?
The Sierra 18-3046 supersedes the 18-3060. The 18-3046 is the current part number; the 18-3060 is the legacy number. Both refer to the same impeller specification.

3. Does this kit include gaskets?
Yes — the 18-3046 includes the impeller and gaskets for the water pump housing. Replace all gaskets at every impeller service.

4. How often should I replace the water pump impeller?
Annually or every 100 hours, whichever comes first. More frequently if the engine is operated in silty or sandy water, or if the engine sits unused for extended periods — static storage causes neoprene blades to take a permanent set.

5. What lubricant should I use to install the impeller?
Dish soap or glycerin — both are safe for neoprene and wash away cleanly. Do not use petroleum-based grease or lubricants, which degrade neoprene impeller blades over time.