Water Distribution Housing – Fits Mercury/MerCruiser 4.3L, 5.0L, 5.7L, 6.2L (Replaces 863631T1)

Water Distribution Housing – Fits Mercury/MerCruiser 4.3L, 5.0L, 5.7L, 6.2L

This water distribution housing is a direct-fit replacement for a range of Mercury and MerCruiser inboard and sterndrive engines. It is compatible with V6 and V8 MPI models (262, 305, 350, 377, 383 CID) manufactured from 1998 onward, including 4.3L, 5.0L, 5.7L, and 6.2L variants.

This assembly directly replaces OEM part numbers: 863631T1, 863631A1/863631T1, and 863444T2.

• Engineered for a direct OEM replacement fit.
• Features a manual drain system with 3-point and 7-point drains for standard cooling.
• Constructed from a durable metal and plastic composite to withstand the marine environment.

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 Distribution Housing Assembly (replaces 863631T1)
• 2 x Manual Drain Plugs
• 2 x O-Rings

Installation Guide

1. Safety First: Before starting, disconnect the boat's battery and ensure the engine is cool.
2. Drain System: Completely drain the cooling system to avoid spills and messes.
3. Disconnect Hoses: Carefully identify and disconnect all hoses attached to the water distribution housing. Note their positions for reassembly.
4. Remove Old Housing: Unbolt and remove the original housing from the engine block.
5. Clean Surface: Thoroughly clean the mounting surface on the engine, removing any old gasket material or sealant residue.
6. Install New Housing: Position the new housing with its seals and gaskets. Bolt it securely in place, tightening bolts to the manufacturer's recommended torque specifications.
7. Reconnect Hoses: Reattach all hoses to their correct ports on the new housing and secure the clamps.
8. Refill and Check: Refill the cooling system with the appropriate coolant. Reconnect the battery.
9. Final Inspection: Start the engine and let it run for several minutes while carefully checking the new housing and all connections for any leaks.

Troubleshooting & FAQ

Q: How do I confirm this part fits my specific engine model?

A: The best way is to compare your original part's number to the numbers listed in our Part Number Cross-Reference table. Also, check your engine model and year against the Compatible Engine Models list. Visual comparison with our product photos is also recommended.

Q: What are the symptoms of a failing water distribution housing?

A: Common signs include coolant leaks around the housing, engine overheating, and visible cracks or corrosion on the part itself. A failure can lead to serious engine damage if not addressed.

Q: Is any special maintenance required for this part?

A: No special maintenance is needed, but it should be inspected regularly for signs of wear, cracks, or leaks as part of your routine engine maintenance, especially before winterization or after long periods of storage.

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.