Water Distribution Housing – Fits Mercury/MerCruiser 4.3L, 5.0L, 5.7L, 6.2L (Replaces 863631T1, 863802T2)

$42.80

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Water Distribution Housing – Fits Mercury/MerCruiser 4.3L, 5.0L, 5.7L, 6.2L (Replaces 863631T1, 863802T2) is backordered and will ship as soon as it is back in stock.

Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Water Distribution Housing is an essential cooling system component designed for a wide range of Mercury MerCruiser inboard and sterndrive engines. It is fully compatible with 4.3L, 5.0L, 5.7L, and 6.2L MPI models (V6 & V8, including 262, 305, 350, 377, and 383 CID) manufactured from 1998 onward.

This assembly is a direct replacement for Mercury/MerCruiser part numbers 863631T1, 863631A1, 863802T2, and 863444T2.

Engineered for direct OEM replacement bolt-on installation.
Features a durable composite metal and plastic housing construction.
Equipped with a manual drain system for both 3-point and 7-point (standard cooling) configurations.

Part Number Matrix

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

Brand	Part Number
Mercury/MerCruiser	863631T1
Mercury/MerCruiser	863631A1
Mercury/MerCruiser	863802T2
Mercury/MerCruiser	863444T2

Engine & Model Compatibility

Confirm your engine model and year in the table below to ensure correct fitment.

This housing component is designed for a wide array of V6 and V8 MerCruiser and Mercury engines from 1998 and later, including MPI, MIE, and various Alpha/Bravo drive configurations.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
MerCruiser	350 MAG MPI	300	4-Stroke	1998–Present	863631T1	Alpha/Bravo, Horizon variants
MerCruiser	350 MAG MPI SKI	300	4-Stroke	1998–Present	863631T1
MerCruiser	350 MAG MPI MIE	300	4-Stroke	1998–Present	863631T1	Marine Industrial Engine
MerCruiser	350 MPI ALPHA	300	4-Stroke	1998–Present	863631T1
MerCruiser	377 MAG MPI	320	4-Stroke	1998–Present	863631T1	Bravo, EC variants
MerCruiser	383 MAG STROKER	350	4-Stroke	1998–Present	863631T1	Inboard
MerCruiser	4.3L MPI	220	4-Stroke	1998–Present	863631T1	Alpha/Bravo, EC variants
MerCruiser	5.0L MPI	260	4-Stroke	1998–Present	863631T1	Alpha/Bravo, EC variants
MerCruiser	5.7L MPI	300	4-Stroke	1998–Present	863631T1	All variants including MIE, Horizon MIE, Ski, Towsport
MerCruiser	6.2L MPI	320–377	4-Stroke	1998–Present	863631T1	All variants including Bravo, Horizon, MIE, Ski
Mercury	V6	-	4-Stroke	1998–Present	863631T1	262 CID
Mercury	V8	-	4-Stroke	1998–Present	863631T1	305, 350, 377 CID

Technical Specs

Product Type: Water Distribution Housing Assembly
Installation: Direct OEM replacement
Connection: Bolt-on
Housing Material: Metal and plastic composite construction
Housing Color: Black/Silver
Weight: 0.81 kg (1.8 lbs)
Fitting Type: Manual drain system
Drain Plug Thread Size: .500-13
Cooling System Support: 3-point and 7-point drain (standard cooling)
Warranty: 90 day (aftermarket version), OEM warranty varies by manufacturer

What’s in the Box

1 x Water Distribution Housing
2 x Manual Drain Plugs
2 x O-Rings

Installation Notes

Disconnect the boat's battery. Ensure the engine is completely cool.
Drain the engine cooling system by opening the appropriate drain plugs.
Carefully label and disconnect all hoses attached to the existing water distribution housing.
Unbolt and remove the old housing from the engine block. Note the position of any brackets.
Thoroughly clean the engine mounting surface to remove any old gasket material or sealant.
Position the new housing assembly, ensuring any O-rings or gaskets are seated correctly.
Install and tighten the mounting bolts to the manufacturer's recommended torque specification.
Reconnect all hoses to their correct ports and securely tighten the clamps.
Close the new drain plugs and refill the cooling system with the appropriate coolant.
Reconnect the battery. Start the engine and carefully check for any leaks around the new housing and hoses.

Troubleshooting & FAQ

How do I know if this housing fits my engine?

First, check the compatibility table on this page. If your engine model and year are listed, it is a likely fit. Second, cross-reference the part number on your existing housing with the numbers in our Part Number Matrix (863631T1, 863802T2, etc.). Finally, visually compare your part to our product photos.

What are common signs of a failing water distribution housing?

The most common signs are coolant leaks (leaving a pink or green residue), visible cracks or damage on the housing itself, and engine overheating alarms. A cracked housing can lead to significant coolant loss and serious engine damage if not addressed.

What is the purpose of the manual drain plugs?

The drain plugs allow you to completely drain water from the engine block and cooling manifolds. This is a critical step for winterization in cold climates to prevent water from freezing and cracking the engine block.

Is this a replacement for the 3-point or 7-point drain system?

This housing is compatible with both 3-point and 7-point (standard cooling) manual drain systems used on MerCruiser engines.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Our parts are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free for most orders, and expedited options will appear at checkout if available for your location.

Warranty & returns?

This part is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.

Safety & Important Info

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

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
Fast Global Fulfillment — We offer free standard delivery to most regions with a typical transit time of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

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