Sierra Marine Water Pump Impeller 18-3016-1 – Mercury / Mariner V6 Outboard Replacement
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The Sierra 18-3016-1 Water Pump Impeller is a direct replacement raw water pump impeller designed for Mercury and Mariner V6 outboard engines. This impeller is responsible for drawing cooling water through the lower unit and circulating it through the engine to maintain proper operating temperature.
Constructed from high-quality, flexible marine-grade rubber, this impeller delivers reliable water flow and long service life in both freshwater and saltwater environments. Replacing a worn impeller is essential to prevent overheating and ensure optimal engine performance.
Engineered to meet or exceed OEM specifications, this impeller provides dependable fit and function for routine maintenance or repair.
Key Features
- Direct replacement raw water pump impeller
- Flexible rubber vanes for efficient water flow
- Precision-fit hub for secure installation
- Maintains proper engine cooling performance
- Marine-grade construction for durability
- Sierra limited lifetime warranty
Engine Compatibility
Mercury / Mariner Outboards
- V6 135 HP
- V6 150 HP
- V6 175 HP
- V6 200 HP
- V6 225 HP
➡️ Fits a wide range of Mercury/Mariner V6 outboards using compatible water pump assemblies
Serial Number Fitment Notice
Fitment depends on:
- Engine model and year
- Gearcase type
- Water pump configuration
⚠️ Always confirm using:
- Engine serial number
- OEM part number match (18-3016-1)
When This Part Needs Replacement
Replace the impeller if you notice:
- Weak or no telltale stream
- Engine overheating
- Reduced cooling performance
- Cracked, missing, or stiff vanes
- After seasonal storage
Recommended service interval: every 100 hours or annually
Installation Notes
- Lubricate impeller before installation
- Install with correct vane rotation
- Inspect wear plate and pump housing
- Ensure proper key alignment
- Replace seals/gaskets if worn
Alternate / Superseded Part Numbers
OEM Cross References
- Mercury: 47-96148T8, 96148T8
Aftermarket Cross References
- Sierra: 18-3016-1
- Mallory: 9-45607
- GLM: 12031
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
💡 Parts Desk Insight
On V6 outboards, the impeller does the most work at higher RPM. A worn impeller might still cool fine at idle but struggle once you’re on plane.
Replacing it regularly is one of the best ways to keep your engine protected and running strong 👍
💡 Parts Desk Insight
Some Mercury applications use composite hub impellers instead of brass splined hubs. Matching the hub style is just as important as size—installing the wrong type can lead to poor fitment or premature failure.
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.