Water Pump Impeller Kit – Fits MerCruiser Bravo 1, 2, 3 & Inboard Engines 4.3L-7.4L V8

Water Pump Impeller Kit – Fits MerCruiser Bravo 1, 2, 3 & Inboard Engines 4.3L-7.4L V8

This water pump impeller service kit is designed for MerCruiser Bravo 1, 2, 3 sterndrives and inboard engines. It is compatible with 4.3L, 5.0L, 5.7L, and 7.4L V8 engines manufactured from 1988 and up (serial number B664190 and up) that are equipped with a one-piece pump housing and a serpentine belt.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, ensuring a precise fit for your engine's raw water cooling system.

• Complete Kit: Includes the impeller, wear plate, and O-ring(s) needed for a full service.
• Durable Material: The impeller is made from high-quality neoprene rubber for reliable performance in raw water/sea water applications.
• Engine-Mounted Design: Specifically for engine-mounted, one-piece pump housings.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below. For Mercury owners, here’s a guide to help you identify your engine’s serial/model: Mercury Serial Number Guide. You can also review exploded diagrams to verify part numbers: Mercury Parts Diagrams & Catalog.

Technical Specifications

Package Contents

• 1 x Water Pump Impeller (Replaces 18-3087)
• 1 x Wear Plate (Replaces 18-3350)
• 1-2 x O-Ring(s) (Replaces 18-7163-9) - Note: Kit may contain one or two O-rings.

Installation Guide

Follow these general steps to replace your water pump impeller. Refer to your engine’s service manual for detailed instructions.

1. Disconnect Power: Disconnect the battery to prevent accidental starting.
2. Access the Pump: Locate the raw water pump on the engine. It is typically belt-driven. You may need to remove a serpentine belt to access it.
3. Remove Hoses: Loosen the clamps and detach the inlet and outlet water hoses from the pump housing.
4. Remove Pump Housing: Unscrew the bolts securing the pump housing cover or the entire pump assembly. Keep track of bolt order and length.
5. Extract Old Impeller: Carefully remove the old impeller from the housing. You may need impeller pullers or pliers. Note the orientation of the blades.
6. Clean Housing: Clean the inside of the housing and the wear plate of any debris, corrosion, or old gasket material. Inspect for scoring or damage.
7. Install New Components: Install the new wear plate and O-ring/gasket. Lightly lubricate the new impeller with water or soap and insert it while turning it in the direction of engine rotation to bend the vanes correctly.
8. Reassemble Housing: Secure the housing cover, ensuring an even seal. Tighten bolts to the manufacturer's recommended torque.
9. Reconnect Hoses & Belt: Reattach the water hoses and the serpentine belt, ensuring proper tension.
10. Test for Leaks: Reconnect the battery. Start the engine and immediately check for proper water flow and any leaks around the pump housing.

Troubleshooting & FAQ

Q: How do I confirm this impeller kit fits my specific MerCruiser engine?
A: Start by checking your engine's model, year, and serial number against the "Compatible Engine Models" table above. This kit is for models from 1988 and up (Serial #B664190+) with a one-piece pump housing and serpentine belt. Cross-reference your existing part number with our "Part Number Cross-Reference" table to ensure it matches.

Q: What are the signs of a failing water pump impeller?
A: Common signs include the engine running hotter than normal, a "low water pressure" alarm, and a reduced stream of water from the exhaust/tell-tale outlet. Visual inspection may show cracked, brittle, or missing vanes on the impeller.

Q: How often should I replace my water pump impeller?
A: For preventative maintenance, it is recommended to inspect the impeller annually and replace it every 1-2 years, or every 100-200 hours of operation, depending on usage conditions (e.g., saltwater vs. freshwater).

Q: OEM vs. Aftermarket?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.