Impeller Kit – Fits Westerbeke Generators (Replaces 33112)
This impeller kit is designed for a wide range of Westerbeke marine generators, including models from 6.5 kW to 20.0 kW. It directly replaces OEM part number 33112, but compatibility can vary based on the specific generator's configuration (60Hz vs. 50Hz models) and the existing raw water pump installed.
It serves as a direct cross-reference for several other aftermarket and OEM part numbers, ensuring broad compatibility. Please consult the cross-reference table and compatible models list to ensure proper fitment.
- Direct replacement for simplified installation.
- Includes one impeller and a variety of gaskets and an O-ring to service multiple pump variations.
- Constructed from durable neoprene with a brass insert for reliable performance in marine environments.
Part Number Cross-Reference
Use this table to confirm equivalent part numbers across OEM and aftermarket brands.
| Brand |
Part Number |
| Westerbeke |
33112 |
| Westerbeke |
11764 |
| Westerbeke |
33100 |
| Sierra |
23-3302 |
| Sierra |
23-2000 |
| Sierra |
23-3310 |
| JMP |
7110-01K |
| Sherwood |
10077 / 10077K |
| Onan |
132-0375 / 132-0379 / 132-0498 / 541-1519 |
| Crusader |
727103 |
| Chris Craft |
16.80-90047 |
| Universal |
287439 |
Compatible Generator Models
Confirm your engine model/year in the table below.
| Brand |
Model |
Rated Output |
Frequency |
OEM Part No. |
Notes |
| Westerbeke |
6.5 TWG |
6.5 kW / 4.9 kW |
60Hz / 50Hz |
33112 |
|
| Westerbeke |
8.0 TWG |
8.0 kW / 6.4 kW |
60Hz / 50Hz |
33112 |
|
| Westerbeke |
8.5 BTG |
8.5 kW / 6.5 kW |
60Hz / 50Hz |
33112 |
|
| Westerbeke |
8.5 BTGA |
8.5 kW / 6.8 kW |
60Hz / 50Hz |
33112 |
|
| Westerbeke |
11.0 TWG |
11.0 kW / 8.5 kW |
60Hz / 50Hz |
33112 |
|
| Westerbeke |
12.5 BTG |
12.5 kW / 10.0 kW |
60Hz / 50Hz |
33112 |
|
| Westerbeke |
15.0 BTG/A |
15.0 kW / 12.0 kW |
60Hz / 50Hz |
33112 |
|
| Westerbeke |
20.0 WTA |
20.0 kW / 16.0 kW |
60Hz / 50Hz |
33112 |
|
Technical Specifications
| Specification |
Value |
| Product Type |
Marine Generator Impeller Kit |
| Installation |
Direct OEM replacement |
| Connection |
Key Drive |
| Housing Material |
Neoprene (impeller) with Brass insert |
| Housing Color |
Black |
| Dimensions |
57mm diameter × 20mm width (impeller) |
| Weight |
0.14 kg (0.30 lbs) approx. (impeller only) |
| Fitting Type |
Key Drive Impeller |
| Warranty |
1 year manufacturer warranty (JMP); Sierra lifetime warranty on materials and workmanship |
| Other Technical Attributes |
12 impeller blades; 12.7mm (1/2") shaft diameter |
Package Contents
- 1 x Impeller (Replaces Westerbeke 33112)
- 1 x Gasket (GAK0041)
- 1 x Gasket (GAK0042)
- 1 x Gasket (GAK0043)
- 1 x O-Ring (ORG0040)
Note: Some applications may not require all items included in the kit.
Installation Guide
Professional installation is recommended. The following is a general guide:
- Shut off the seacock and disconnect power to the generator.
- Place an absorbent pad under the raw water pump to catch spills.
- Loosen and remove the screws on the pump's faceplate/cover.
- Gently pry off the cover. Be careful not to damage the housing or cover.
- Using impeller pullers or two flat-head screwdrivers, carefully grip and pull the old impeller straight out of the pump housing.
- Clean the interior of the pump housing and inspect for scoring or debris.
- Lubricate the new impeller and the inside of the pump housing with a water-based lubricant or glycerine.
- Install the new impeller by pushing it into the housing while turning the shaft to bend the blades in the correct direction.
- Clean the cover plate and install the correct new gasket or O-ring for your pump model.
- Re-attach the cover plate, tightening the screws in a star pattern to ensure an even seal.
- Open the seacock, restore power, and start the generator. Immediately check for water leaks and verify proper water flow from the exhaust.
Troubleshooting & FAQ
Q: How do I know if this impeller fits my Westerbeke generator?
A: This kit is designed for a wide range of Westerbeke generators from 6.5 kW to 20.0 kW. The best way to confirm fitment is by matching your generator's OEM part number (33112) with our cross-reference list. Additionally, verify your model is listed in the compatible models table on this page.
Q: What are the signs that my impeller needs replacing?
A: The most common signs of a failing impeller are generator overheating, a noticeable reduction in water flow from the exhaust outlet, or visible damage such as cracks, missing blades, or brittle rubber found during inspection.
Q: How often should I replace my generator's impeller?
A: As a crucial part of preventative maintenance, you should inspect the impeller annually and plan to replace it every 1-2 years. The replacement interval depends heavily on usage hours, water conditions (sandy/silty water causes faster wear), and periods of disuse.
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 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.
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.