Impeller Kit – Fits Westerbeke Marine Diesel Generators & Engines (Replaces 48500, 048500)

This impeller repair kit is designed for Westerbeke marine diesel generators and engines equipped with Sea Water Pump models 48080/048080 and 37431/037431 (manufactured after March 2004). It is compatible with a wide range of generators from the 5.7 BTD to the 15.0 BTDC (both 50 Hz and 60 Hz models) and select marine diesel engines equipped with the 048080 sea water pump.

This kit serves as a direct replacement for Westerbeke part numbers 48500 and 048500, along with several aftermarket equivalents.

• Installation: Designed for marine raw/sea water cooling systems with a direct mount to the pump.
• Important Fitment Note: This kit is ONLY compatible with pumps manufactured from March 2004 onwards, which feature the new style round 6-bolt cover. It will NOT fit older pump model 33636 (which has a scalloped cover). Please verify your pump model before ordering.
• Kit Contents: Includes the impeller, O-ring, and screw for a complete service.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the tables below. Important: Compatibility is based on engines equipped with the Westerbeke 048080 sea water pump (post-March 2004). Always verify your pump model number before purchasing.

Westerbeke Marine Diesel Generators

Westerbeke Marine Diesel Engines

Note: The engines listed below are compatible only when equipped with the post-March 2004 sea water pump (model 048080). Earlier production units with pump model 033636 use a different impeller kit (Westerbeke 034440). Please verify your pump model before ordering.

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (Replaces 48500/048500)
• 1 x O-Ring (Replaces 48359)
• 1 x Screw (Replaces 34463)

Installation Guide

IMPORTANT: Before starting, confirm your sea water pump is a model 48080/048080 or 37431/037431 manufactured after March 2004. These pumps have a round, 6-bolt cover. This kit is NOT compatible with older pump model 33636, which has a scalloped cover.

1. Turn off the engine and close the sea cock (water intake valve) to prevent water from entering the vessel.
2. Locate the sea water pump on the engine.
3. Unscrew the 6 bolts on the pump cover plate.
4. Carefully pry off the cover. Note that some water may spill out.
5. Use pliers to grip the hub of the old impeller and pull it straight out.
6. Clean the inside of the pump housing and the cover plate, removing any old gasket material or debris.
7. Lightly lubricate the new impeller and the inside of the pump housing with a suitable marine lubricant.
8. Install the new impeller by pushing it into the housing while turning it in the direction of engine rotation. Ensure the blades are correctly oriented.
9. Place the new O-ring into the groove on the pump body.
10. Reinstall the cover plate and tighten the screws in a star pattern to ensure even pressure.
11. Open the sea cock.
12. Start the engine and immediately check for leaks around the pump cover. Confirm water is exiting the exhaust, indicating proper pump operation.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my pump?
A: This impeller kit is specifically for Westerbeke sea water pumps 48080/048080 and 37431/037431 made after March 2004. The easiest way to identify a compatible pump is by its cover: it must be the new style round cover secured by 6 bolts. If your pump cover is scalloped near the 4 and 8 o'clock positions, it is an older, incompatible model (033636), which uses a different impeller kit (Westerbeke 034440).

Q: What are the signs of a failing impeller?
A: Common signs include engine overheating, reduced water flow from the exhaust outlet, and visible cracks or missing blades on the impeller itself. We recommend inspecting the impeller annually.

Q: How often should I replace my engine's impeller?
A: For most applications, it is recommended to replace the impeller every 1-2 years or every 100-200 hours of operation, whichever comes first. This can vary based on usage and water conditions (e.g., sandy or debris-filled water may require more frequent changes).

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty from JLM Marine against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.
• For diesel engines (12C Two through 44C Four series): This kit is only compatible with engines that have been fitted with the post-March 2004 sea water pump (model 048080). Earlier engines with pump model 033636 require a different impeller kit (Westerbeke 034440).

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.