Circulation Water Pump for OMC 2.5 3.0 4.0 L 984360

Circulation Water Pump – Fits OMC 2.5L, 3.0L, 4.0L Marine Engines

This is an aftermarket circulation water pump for OMC and Volvo Penta stern drive marine engines. It is designed to fit 2.5L, 3.0L, and 4.0L GM-based marine engines from 1982–1993.

This component directly replaces OMC part numbers 984360, 986779, 3854017, 3858340, 509356 and Volvo Penta part numbers 3854017, 3858340.

• Engine block-mounted circulation pump for raw water cooling systems.
• Features a durable cast aluminum housing with a brass impeller for corrosion resistance in fresh and saltwater.
• Includes the necessary mounting gasket 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.

Technical Specifications

Package Contents

• 1 x Circulation Water Pump (984360/3854017)
• 1 x Gasket

Explosion Diagram

Installation Guide

1. Drain the cooling system completely to avoid spills. Disconnect the negative battery terminal.
2. Loosen the belt tensioner and remove the serpentine belt from the pump pulley.
3. Unscrew the mounting bolts holding the old water pump to the engine block.
4. Gently tap the old pump to break the seal and remove it. Be prepared for some residual coolant leakage.
5. Clean the mounting surface on the engine block thoroughly, removing all old gasket material and residue.
6. Place the new gasket onto the engine block, aligning it with the bolt holes.
7. Mount the new water pump, ensuring it sits flush against the gasket.
8. Hand-tighten the mounting bolts, then torque them to the manufacturer's specified values in a star pattern.
9. Reinstall the pulley and serpentine belt, ensuring proper tension.
10. Reconnect all hoses to the new pump and secure the clamps.
11. Refill the cooling system with the appropriate coolant mixture. Reconnect the battery.
12. Start the engine, check for leaks, and top off the coolant as the system bleeds air.

Troubleshooting & FAQ

Q: How do I confirm this pump fits my OMC or Volvo Penta engine?

A: The best method is to match the part number from your old pump to one of the numbers listed in our cross-reference table. Additionally, verify your engine model and year falls within the ranges specified in the compatible models list.

Q: What makes this pump suitable for saltwater use?

A: This pump is constructed with a brass impeller, which offers superior corrosion resistance compared to standard steel or plastic impellers, making it ideal for both saltwater and freshwater marine environments.

Q: What are the common signs of a failing circulation water pump?

A: Key symptoms include engine overheating, visible coolant leaks from the pump's weep hole or gasket, a wobbly or noisy pump pulley, or a loose-feeling pump shaft.

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.