863444T1 Water Distribution Housing for Mercury Mercruiser | JLM Marine

Water Distribution Housing – Fits Mercury/Mercruiser 4.3/5.0/5.7/6.2L Inboard Engines | 863444T1

This Water Distribution Housing is designed for MerCruiser inboard engines, including 4.3L, 5.0L, 5.7L, and 6.2L models. Engineered to deliver reliable cooling system performance, this housing ensures proper water distribution throughout your engine block, preventing overheating and maintaining optimal operating temperatures.

This aftermarket replacement directly replaces OEM part number 863444T1 from Mercury/Mercruiser, offering a cost-effective solution without compromising quality or fitment.

• Manual Drain Configuration: The most common alternative (OEM 863444T1) for easy maintenance
• Precision-engineered to OEM specifications for direct-fit installation
• Compatible with standard cooling systems on popular MerCruiser inboard platforms

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 × Water Distribution Housing (OEM 863444T1)

Installation Guide

1. Preparation: Ensure the engine is completely cool and disconnect the battery before beginning work. Drain the cooling system to prevent spills.
2. Remove Old Housing: Disconnect all hoses attached to the existing water distribution housing and unbolt it from the engine block.
3. Clean Surfaces: Thoroughly clean the mounting surface on the engine block, removing all old gasket material and debris.
4. Inspect Components: Check hoses, clamps, and connections for wear or damage; replace if necessary.
5. Position New Housing: Align the new water distribution housing with the mounting holes on the engine block.
6. Secure Housing: Install and torque mounting bolts to manufacturer specifications in a crisscross pattern to ensure even sealing.
7. Reconnect Hoses: Attach all cooling system hoses to the appropriate ports on the new housing. Secure with new clamps if the originals are worn.
8. Refill Coolant: Refill the cooling system with the appropriate coolant mixture per your engine manual.
9. Bleed Air: Follow your engine's bleeding procedure to remove trapped air from the cooling system.
10. Test Operation: Reconnect the battery, start the engine, and monitor for leaks while checking cooling system operation. Inspect all connections under operating temperature.

Troubleshooting & FAQ

Q: How do I know which distribution housing alternative I need?
A: There are four alternatives: Manual Drain (863444T1), Rod Actuated, Air Actuated (closed cooling), and Air Actuated (standard cooling). The Manual Drain version (863444T1) is the most common. Verify your current configuration or consult your engine manual.

Q: What are signs that my water distribution housing needs replacement?
A: Common symptoms include coolant leaks around the housing, engine overheating, visible cracks in the housing body, or corrosion damage. If you notice any of these issues, replacement is recommended.

Q: Can I use this housing on both closed and standard cooling systems?
A: This Manual Drain version (863444T1) is designed for standard cooling applications. If you have a closed cooling system or air-actuated setup, verify compatibility with your specific engine configuration before installation.

Q: How often should the water distribution housing be inspected or replaced?
A: Inspect the housing annually during routine maintenance or whenever you service the cooling system. Replace it if you observe leaks, cracks, or excessive corrosion, or as part of a comprehensive cooling system overhaul.

Q: Is this an OEM part or 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.