Water Distribution Housing – Fits Mercury/MerCruiser 4.3L-6.2L MPI (Replaces 863802T2, 863802-A1)

$138.99

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Water Distribution Housing – Fits Mercury/MerCruiser 4.3L-6.2L MPI (Replaces 863802T2, 863802-A1) is backordered and will ship as soon as it is back in stock.

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Product Details

This is a genuine Mercury Marine Water Distribution Housing – Fits Mercury/MerCruiser Closed Cooling System (Replaces 863802T2), designed for air-actuated closed cooling systems on various MerCruiser marine engines from 1999 and newer, including 4.3L, 5.0L, 5.7L, and 6.2L MPI models. The housing manages coolant flow throughout the engine and features distinctive white and orange air fittings on the side for easy identification.

This part is a direct replacement for Mercury/MerCruiser part numbers 863802T2 and the superseded 863802-A1.

Designed for direct OEM replacement on air-actuated closed cooling systems.
Easily identified by the distinctive white and orange air fittings.
Constructed from durable aluminum casting for longevity in marine environments.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number	Superseded By	Notes
Mercury/MerCruiser	863802-A1	863802T2	Superseded part number
Mercury/MerCruiser	863802T2		Current OEM part number

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
MerCruiser	4.3L MPI ALPHA/BRAVO	220	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	4.3L MPI ALPHA/BRAVO EC	220	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	5.0L MPI ALPHA/BRAVO	260	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	5.0L MPI ALPHA/BRAVO EC	260	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	350 MAG MPI ALPHA/BRAVO	300	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	350 MAG MPI HORIZON ALPHA/BRAVO	300	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	350 MAG MPI ALPHA/BRAVO EC	300	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	350 MAG MPI HORIZON ALPHA/BRAVO EC	300	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	350 MAG MPI MIE	300	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	350 MAG MPI HORIZON MIE	300	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	350 MPI ALPHA	300	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	377 MAG MPI BRAVO	320	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	377 MAG MPI BRAVO EC	320	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	383 MAG STROKER INBOARD	350	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	5.7L MPI MIE	325	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	5.7L MPI MIE EC	325	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	5.7L MPI HORIZON MIE	325	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	6.2L MPI MIE	350-377	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	6.2L MPI MIE EC	350-377	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	6.2L MPI HORIZON MIE	350-377	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	6.2L BS	350-377	4-Stroke	2022	863802T2	Inboard configuration
MerCruiser	MX 6.2L MPI BRAVO	320	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	MX 6.2L MPI HORIZON BRAVO	320	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	MX 6.2L MPI MIE	320	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	MX 6.2L MPI HORIZON MIE	320	4-Stroke	1999–Up	863802T2	MIE = Marine Inboard Engine
MerCruiser	4.5L MPI 200 Alpha/Bravo	200	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	4.5L MPI 200 Alpha/Bravo EC	200	4-Stroke	1999–Up	863802T2	EC = Emissions Control
MerCruiser	4.5L MPI 250 Alpha/Bravo	250	4-Stroke	1999–Up	863802T2	Closed cooling system only
MerCruiser	4.5L MPI 250 Alpha/Bravo EC	250	4-Stroke	1999–Up	863802T2	EC = Emissions Control

Technical Specs

Product Type: Water Distribution Housing
Installation: Direct OEM replacement
Fuel Type: Gasoline
Connection: Air-actuated system with white and orange air fittings
Housing Material: Aluminum casting
Housing Color: Natural aluminum
Dimensions: 218.4 × 195.6 × 180.3 mm (8.6 × 7.7 × 7.1 in)
Weight: 0.54 kg (1.2 lbs)
Fitting Type: Air-actuated closed cooling
Operating Temperature: Marine engine operating range
Warranty: 1 year Mercury Marine factory warranty
Other Technical Attributes: Air-actuated; Closed cooling system compatible

What’s in the Box

1 x Water Distribution Housing (863802T2)

Installation Notes

Disconnect the boat's battery before beginning work.
Place a catch pan under the engine and drain the closed cooling system.
Carefully label and disconnect all hoses and air lines attached to the old water distribution housing.
Remove the mounting bolts securing the old housing and carefully lift it away from the engine.
Thoroughly clean the mounting surface on the engine, ensuring it is free of old gasket material and corrosion.
Position the new housing onto the engine, aligning it with the mounting holes.
Install and tighten the mounting bolts to the manufacturer's specified torque.
Reconnect all hoses and air lines to their corresponding fittings on the new housing.
Refill the cooling system with the appropriate coolant mixture.
Reconnect the battery, start the engine, and carefully check for any leaks around the housing and hose connections.

Troubleshooting & FAQ

How do I confirm this housing fits my engine?

This is a commonly mis-ordered part. Please verify your engine model, year, and serial number against our compatibility table. Crucially, confirm your engine uses an air-actuated closed cooling system; this housing is identifiable by its distinct white and orange air fittings.

What are the signs of a failing water distribution housing?

Common failure symptoms include visible coolant leaks from the housing body or its connection points, engine overheating alarms, and low coolant levels. You may also see physical cracks or corrosion on the housing itself during a visual inspection.

Is this part for open (raw water) or closed cooling systems?

This housing is designed exclusively for MerCruiser engines equipped with air-actuated closed cooling (freshwater) systems. It will not work with raw-water cooled engines.

What is the difference between 863802T2 and 863802-A1?

The part number 863802T2 is the current version that supersedes the older 863802-A1. They are functionally identical, and the T2 is the correct direct replacement for the A1.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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