Sierra Marine Water Pump Kit 18-3390 – Johnson / Evinrude 85-300HP V4 V6 Cooling System Rebuild
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The Sierra 18-3390 Water Pump Kit is a complete internal rebuild kit designed for Johnson and Evinrude high-horsepower outboards equipped with large gearcases. This kit restores proper water flow through the engine, preventing overheating and ensuring reliable cooling performance under load.
This is a “without housing” kit, meaning it includes all critical internal components while reusing the existing pump housing. Ideal for routine maintenance or correcting weak water pressure, overheating, or impeller wear.
Manufactured to meet or exceed OEM specifications, Sierra components provide dependable fit, durability, and long service life in demanding marine environments.
Key Features
- Complete internal water pump rebuild kit (housing not included)
- Includes impeller, wear plate, cup, gaskets, seals, and hardware
- Designed for high-horsepower OMC outboards with large gearcases
- Restores cooling system performance and water pressure
- Direct OEM replacement fit and function
- Sierra limited lifetime warranty
Engine Compatibility
Johnson / Evinrude / OMC Outboards (Large Gearcase – 1979 & Newer)
- 85 HP
- 90 HP
- 100 HP
- 115 HP
- 135 HP
- 140 HP
- 150 HP
- 175 HP
- 200 HP
- 225 HP
- 235 HP
- 250 HP
- 300 HP
➡️ Fits V4 and V6 crossflow and looper engines using large gearcases.
Serial Number Fitment Notice
This kit is for large gearcase applications only.
⚠️ Always confirm:
- Gearcase size (large vs small)
- Engine model and year
- OEM part number match
Serial number verification is strongly recommended to avoid misfit.
When This Part Needs Replacement
Replace the water pump kit if you notice:
- Weak or no telltale stream
- Engine overheating
- Reduced cooling at idle
- Impeller cracking, swelling, or hardening
- Long storage periods (dry impeller damage)
Recommended service interval: every 100 hours or annually
Installation Notes
- Housing is not included — inspect and replace if worn
- Install impeller with correct rotation direction
- Use marine grease during installation
- Replace seals and grommets to prevent air leaks
- Torque fasteners evenly to OEM specifications
Alternate / Superseded Part Numbers
OEM Cross References
- Johnson / Evinrude / OMC:
- 0395060
- 0434421
- 0435447
- 5001594
Aftermarket Cross References
- Mallory: 9-48210
- GLM: 12104
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
💡 Parts Desk Insight
This is a big gearcase kit — one of the most common mistakes is ordering a small gearcase version.
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.