Description

The Westerbeke Impeller Kit 48500 is a complete raw water pump service kit designed for Westerbeke marine diesel engines and generators. This kit includes a precision-molded neoprene impeller along with sealing components and hardware to restore proper cooling system performance and ensure reliable operation.

The impeller is responsible for drawing seawater through the cooling system. Over time, the flexible vanes can wear, harden, or break, reducing water flow and increasing the risk of overheating. Replacing the impeller at recommended intervals helps maintain consistent cooling and protects your engine or generator from damage.

This kit is widely used across Westerbeke generator and engine platforms, making it a key maintenance item for dependable marine operation.

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Key Features

• Complete raw water pump impeller service kit
• Marine-grade neoprene impeller construction
• 6-blade flexible impeller design
• Includes O-ring, gasket, and mounting hardware
• Maintains proper raw water flow and cooling performance
• OEM-equivalent fit and function

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Engine Compatibility

Westerbeke Marine Diesel Generators

• 5.7 BTD
• 6.0 BTDA
• 7.5 BTD / BTDA
• 7.6 BTD
• 8.0 BTDA
• 8.3 BTD
• 9.4 BTDA / BTDB
• 10.0 BTD / BTDA
• 11.0 BTD
• 12.0 BTDC
• 12.5 BTDA / BTDB
• 15.0 BTDC

Westerbeke Marine Diesel Engines

• 12C Two
• 20B Two
• 30B Three
• 35C / 35D / 35E Three
• 38B Four
• 42B Four
• 44A / 44B / 44C Four

Fits engines using compatible Westerbeke raw water pumps

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Serial Number Fitment Notice

Fitment depends on:

• Pump model
• Engine model and year
• Pump cover design

Important Fitment Note:

• Fits pumps 48080 / 048080 and 37431 / 037431
• Designed for new-style round 6-bolt cover pumps (2004+)
• Will NOT fit older pump model 33636 (scalloped cover)

Always confirm compatibility using your pump model or engine serial number before ordering.

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Impeller Specifications

• Diameter: 2.0″ (50.8 mm)
• Width: 22 mm
• Shaft: Slotted / pin drive
• Blade Count: 6
• Material: Neoprene rubber

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What’s Included in the Kit

• Impeller
• O-ring
• Gaskets
• Mounting screw / hardware

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When This Part Needs Replacement

Replace the impeller if you notice:

• Reduced or no cooling water flow
• Generator or engine overheating
• Cracked, missing, or stiff vanes
• Reduced output under load

Recommended service interval: every 100–200 hours or annually

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Installation Notes

• Lubricate impeller before installation
• Install with correct vane direction
• Replace all gaskets and O-rings
• Inspect pump housing and wear surfaces
• Verify pump style (round vs scalloped cover) before install

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Alternate / Superseded Part Numbers

OEM Cross References

• Westerbeke: 48500, 048500

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Aftermarket Cross References

• StayCoolPumps: SCP-48500
• Various aftermarket equivalents (QuickMarine, SOXA, etc.)

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Shipping

Shipping: Ships same or next day for fast Canada wide shipping.

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Parts Desk Insight

This is a very common Westerbeke generator impeller—but the pump cover style matters. The newer round 6-bolt pumps and older scalloped pumps use different impellers.

Quick visual check before ordering saves a lot of headaches