Description

The Sierra 18-3016-1 Impeller Kit is a complete raw water pump service kit designed for Mercury and Mariner outboards. This kit includes the impeller along with essential sealing components to restore proper cooling water circulation and protect your engine from overheating.

The impeller is the heart of the cooling system, drawing water through the lower unit and delivering it to the engine. Over time, the rubber vanes can wear, crack, or lose flexibility, reducing cooling efficiency. Replacing the impeller and seals ensures reliable performance and helps prevent costly engine damage.

Manufactured to meet or exceed OEM specifications, this kit delivers dependable operation in both freshwater and saltwater environments.

---

Key Features

• Complete water pump impeller service kit
• Includes impeller, gaskets, and seals (varies by application)
• Restores proper cooling water flow
• Direct OEM replacement fit and performance
• Durable flexible rubber impeller construction
• Sierra limited lifetime warranty

---

Engine Compatibility

Mercury / Mariner Outboards

Commonly used on:

• 90 HP
• 115 HP
• 135 HP
• 150 HP

Fits select Mercury/Mariner V6 outboards using compatible water pump housings.

---

Serial Number Fitment Notice

Fitment depends on:

• Engine model and year
• Lower unit / 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 kit if you notice:

• Weak or no telltale stream
• Engine overheating
• Reduced cooling performance
• Cracked, hardened, or missing impeller vanes
• After seasonal storage

Recommended service interval: every 100 hours or annually

---

Installation Notes

• Install impeller with correct vane rotation
• Lubricate impeller during installation
• Inspect wear plate and pump housing
• Replace all included seals and gaskets
• Ensure proper key alignment on shaft

---

Alternate / Superseded Part Numbers

OEM Cross References

• Mercury: 46-96148A8, 46-96148A1, 96148A8

---

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 most of the work at higher RPM. A worn impeller might still cool fine at idle but can struggle when you’re on plane.

Replacing the full kit ensures proper sealing and consistent water flow, helping avoid overheating when you’re running hard