Sierra 18-3067 Mercury/Mariner/Yamaha Impeller
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The Sierra 18-3067 is a six-blade replacement lower-unit water pump impeller for select Mercury, Mariner and Yamaha outboards. It installs inside the gearcase water pump and circulates cooling water through the engine. The 47-3067 number is a distributor SKU for Sierra part 18-3067. It replaces Mercury/Mariner impellers 47-81604M and 47-84797M, along with Yamaha 689-44352-00-00, 689-44352-01-00 and 689-44352-02-00.
Key Features
- Sierra manufacturer part number: 18-3067
- Distributor SKU: 47-3067
- Six flexible neoprene blades
- Approximately 2-1/4-inch outside diameter
- Approximately 1/2-inch depth
- Designed for select Mercury, Mariner and Yamaha outboards
- Included in Sierra water pump kits 18-3426 and 18-3427
- Supplied as one replacement impeller
- UPC: 030999315199
Engine Compatibility
The strongest documented applications are select Mercury, Mariner and Yamaha outboards in the approximately 20–30 HP range, including many 25 HP applications. Catalogue references associate this impeller with selected engines manufactured from the late 1970s through the 1990s, including certain Mercury 28 HP and Yamaha 25 and 30 HP models. Exact compatibility depends on the complete engine model, production year, serial number and gearcase water pump configuration.
Serial Number Fitment Notice
Do not select this impeller by horsepower alone. Mercury, Mariner and Yamaha used different gearcases and water pump configurations within similar horsepower ranges.
Before ordering, confirm:
- Complete engine model and serial number
- Production year
- Gearcase and water pump assembly
- Original impeller number
- Mercury/Mariner reference 47-81604M or 47-84797M
- Yamaha reference 689-44352-00-00, 689-44352-01-00 or 689-44352-02-00
- Impeller diameter, depth and drive-key arrangement
The original engine water pump diagram provides the most reliable fitment confirmation.
When This Part Needs Replacement
Replace the impeller if:
- Cooling-water discharge becomes weak or intermittent
- The engine begins operating hotter than normal
- An overheat warning activates
- The blades are cracked, torn, stiff or permanently bent
- Rubber fragments are missing
- The centre hub slips inside the impeller
- The engine has been operated without cooling water
- The motor has operated regularly in sandy or silty conditions
- The scheduled water pump service interval has been reached
Running the pump dry or operating in sand and silt can quickly damage the impeller and reduce cooling-water flow.
Installation Notes
Lower-unit removal is normally required to access the water pump assembly. During service:
- Disconnect the ignition and battery where applicable
- Follow the correct shift-linkage and lower-unit removal procedure
- Inspect the pump housing, cup, wear plate, drive key, seals and driveshaft
- Remove broken impeller fragments from the pump and cooling passages
- Lubricate the impeller with clean soapy water or an approved assembly lubricant
- Position the drive key correctly
- Rotate the driveshaft in its normal operating direction while lowering the housing over the blades
- Replace worn gaskets, O-rings and pump components
- Reinstall the lower unit according to the engine service manual
- Confirm strong cooling-water flow before operating under load
Never operate the outboard without an adequate cooling-water supply.
Alternate/Superseded Part Numbers
- Sierra: 18-3067
- Distributor SKU: 47-3067
- Sierra catalogue reference: 118-3067
- Mercury/Mariner: 47-81604M
- Mercury/Mariner: 47-84797M
- Mercury shortened references: 81604M and 84797M
- Yamaha: 689-44352-00-00
- Yamaha: 689-44352-01-00
- Yamaha: 689-44352-02-00
- GLM Marine: 89890
- Mallory Marine: 9-45600
- UPC: 030999315199
Parts Desk Insight
The 47-3067 number can resemble a Mercury OEM number, but it is the distributor SKU for Sierra 18-3067. Because this impeller crosses between Mercury/Mariner and Yamaha applications, matching the original OEM number and pump diagram is more reliable than ordering by horsepower alone.
Compatible & Related Products
Other impellers and water pump kits for Mercury/Mariner and Yamaha outboards available at Marisol Marine:
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.