Water Pump Impeller Kit – Fits Westerbeke Marine Generators 3.3-15.0kW (Replaces 034440, 34440)

Product Details

This Water Pump Impeller Kit – Fits Westerbeke Marine Generators 3.3-15.0kW (Replaces 034440, 34440) is designed for Westerbeke marine generators from 3.3kW to 15.0kW manufactured prior to March 2004. It is engineered specifically for models equipped with the 33636 sea water pump that has an irregular-shaped cover.

This kit serves as a direct replacement for Westerbeke part numbers 034440 and 34440, and also interchanges with Sierra part 23-3307.

• Installs in the raw water (sea water) pump to ensure proper engine cooling.
• Made from durable neoprene to withstand the marine environment.
• Kit includes the impeller, gasket, and necessary mounting screws for a complete service.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Westerbeke Owners: This part is exclusively for generator models produced up to 2004 that use a sea water pump with an irregular (non-round) cover plate. Please verify your pump design before ordering.

Technical Specs

Product Type

Water Pump Impeller Kit

Installation

Raw Water/Sea Water Pump

Impeller Material

Neoprene

Drive Type

Slotted Shaft Pin Drive

Number of Blades

6

Impeller Height

22 mm (0.88 inch)

Overall Diameter

50.8 mm (2 inches)

Shaft Diameter

12 mm (0.47 inch)

Housing Compatibility

Irregular Cover Only (Pre-March 2004)

Pump Application

Sea Water Pump Number 33636

Warranty

1 Year

What’s in the Box

• 1 x Water Pump Impeller (034440)
• 1 x Pump Cover Gasket
• 2 x SS Hex/Slot Screws

Installation Notes

This impeller and gasket are for pre-March 2004 Westerbeke pumps with an irregular-shaped cover. It will NOT fit pumps made after March 2004 that use a round cover with an O-ring seal; those models require impeller kit 48500.

1. Close the seacock to prevent water from entering the vessel.
2. Remove the screws from the water pump cover plate.
3. Carefully remove the cover and old gasket. Note the direction of the old impeller's blades.
4. Use pliers or an impeller puller to remove the old impeller.
5. Clean the inside of the pump housing and the cover plate, checking for any scoring or damage.
6. Lightly lubricate the new impeller with water-based lubricant or glycerine.
7. Insert the new impeller into the housing, rotating it in the direction of engine operation to bend the blades correctly.
8. Place the new gasket on the pump body.
9. Reinstall the cover plate and tighten the screws in a star pattern to ensure even pressure.
10. Open the seacock, start the engine, and immediately check for any leaks around the pump cover.

Troubleshooting & FAQ

Safety & Important Info

• Verify images and specifications against your original part before purchasing. If anything differs—even if your model appears compatible—do not purchase.
• This is an aftermarket replacement part, not an OEM component.
• Professional installation is recommended for safety and optimal performance.

About Sea Sierra

• Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world durability.
• Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
• Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.