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 cooling system rebuild kit designed for high-horsepower Johnson and Evinrude outboards with large gearcases. This kit restores proper water flow through the engine, preventing overheating and ensuring reliable performance under load.
This is a “without housing” kit, meaning it includes all internal wear components but reuses the existing pump housing. Ideal for routine service or restoring engines with reduced water pressure or overheating issues.
Manufactured to meet or exceed OEM specifications, Sierra kits provide dependable fit, durability, and long service life.
Key Features
- Complete internal water pump rebuild kit (no housing)
- Includes impeller, wear plate, cup, seals, gaskets, and hardware
- Designed for large gearcase outboards (high horsepower applications)
- Restores proper cooling water pressure and flow
- OEM-quality construction with Sierra lifetime warranty
Engine Compatibility
Johnson / Evinrude / OMC Outboards
Large Gearcase Models (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 & V6 crossflow and looper engines using large gearcases.
These engines share the same pump design and internal components, making this kit widely cross-compatible across the OMC high-horsepower range.
Serial Number Fitment Notice
This kit fits large gearcase applications only.
⚠️ Always confirm:
- Gearcase size (large vs small)
- Engine model and year
- OEM part number match
Some smaller HP models use different kits — serial number verification is strongly recommended.
When This Part Needs Replacement
Replace the water pump kit if you notice:
- Weak or inconsistent telltale stream
- Overheating at speed
- Reduced cooling at idle
- Impeller damage or hardening
- Engine sitting unused for long periods
Recommended service interval: every 100 hours or annually
Installation Notes
- This kit does NOT include the housing
- Inspect housing and replace if scored or corroded
- Install impeller with correct rotation direction
- Use marine grease during assembly
- Replace grommets and seals to prevent air leaks
- Torque fasteners evenly to spec
Alternate / Superseded Part Numbers
OEM Cross References
- Johnson / Evinrude / OMC:
- 0395060
- 0434421
- 0435447
- 5001594
Aftermarket Cross References
- GLM: 12104
- Mallory: 9-48210
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
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.