Sea Water Pump – Fits Volvo Penta, MerCruiser, OMC 4.3L, 5.0L, 5.7L V6/V8 (Replaces 3853850, 8M0113734)

Sea Water Pump – Fits Volvo Penta, MerCruiser, OMC 4.3L, 5.0L, 5.7L V6/V8

This marine water pump is a bi-directional circulation pump designed for GM V6/V8 marine engines used in raw water cooling systems across multiple brands. It is a direct, engine-mounted replacement for sterndrive and inboard applications.

This pump fits a wide range of models, including Volvo Penta 4.3L, 5.0L, & 5.7L engines (1973+); MerCruiser 4.3L V6, 5.0L & 5.7L V8 engines (1963–2014); and OMC V6/V8 engines (1968–1998). It also fits certain Indmar, Pleasurecraft, and Chrysler small block cooling systems.

• Direct Replacement: Replaces OEM part numbers MerCruiser 8M0113734/3853850, Volvo Penta 3853850, OMC 3853850, and Sierra 18-3599-2.
• Durable Construction: Features a steel housing with a stainless steel back plate and impeller cover for enhanced corrosion resistance.
• Complete Kit: Includes the sea water pump assembly and a new gasket set for a complete installation.

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 MerCruiser 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.

For all other makes, confirm your engine model/year in the tables below.

MerCruiser Applications

Volvo Penta Applications

OMC Applications

Indmar/Chrysler/Other Applications

Technical Specifications

Package Contents

• 1 x Sea Water Pump Assembly (Replaces 8M0113734/3853850)
• 1 x Gasket Set (Replaces Sierra 18-0891)

Installation Guide

1. Safety First: Disconnect the boat's battery before beginning any work.
2. Drain Coolant: Place a catch pan under the engine and drain the raw water cooling system.
3. Remove Hoses: Loosen the hose clamps and carefully detach the inlet and outlet hoses from the pump.
4. Unbolt Old Pump: Remove the mounting bolts securing the old sea water pump to the engine block.
5. Clean Surface: Thoroughly clean the engine mounting surface to remove any old gasket material or corrosion. A clean surface is crucial for a good seal.
6. Position Gasket: Place the new gasket onto the cleaned mounting surface, aligning it with the bolt holes.
7. Mount New Pump: Install the new sea water pump, ensuring it sits flush against the gasket. Hand-tighten the bolts first, then torque them to the manufacturer's specification.
8. Reconnect Hoses: Reattach the raw water hoses to the new pump and securely tighten the clamps.
9. Refill and Test: Reconnect the battery. Refill the cooling system with the appropriate coolant. Start the engine and carefully check for any leaks around the pump and hoses.

Troubleshooting & FAQ

Q: How do I confirm this pump fits my engine?
A: Start by checking the compatible engine model tables provided for MerCruiser, Volvo Penta, and OMC. This pump fits GM-based V6 and V8 marine engines and is a direct replacement for part numbers 8M0113734 and 3853850. Important: It is not compatible with MerCruiser 4.3L V6 engines from 2008 and newer.

Q: What are the signs my sea water pump is failing?
A: Common signs of a failing pump include the engine running hotter than normal or overheating, visible water leaks from the pump body or weep holes, a grinding or rattling noise coming from the pump assembly, or noticeably reduced water flow from the exhaust port.

Q: Is this pump bi-directional? What does that mean?
A: Yes, this pump features a bi-directional design. This means it can circulate water effectively regardless of the engine's rotational direction, making it compatible with both standard and reverse-rotation engines without modification.

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.