42724A3 Water Tube Housing Kit for MerCruiser Alpha Gen 1 | JLM Marine

Water Tube Housing Kit for MerCruiser Alpha Gen 1 – OEM 42724A3

This water tube housing kit is engineered for MerCruiser #1, R, MR, and Alpha One Generation 1 sterndrive applications. It provides a complete water pocket cover and tube assembly to maintain proper cooling system function in your outdrive.

This kit directly replaces MerCruiser part number 42724A3 and GLM part number 12200, offering a comprehensive solution for water tube and pocket cover service.

• Complete assembly includes water tube, pocket cover, gasket, bushing, and mounting bolts
• Designed for Alpha One Generation 1 drives (not compatible with Alpha One Generation II)
• Fits MerCruiser #1, R, MR, and Alpha One sterndrives

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

This complete water tube housing kit includes:

• Water tube
• Water pocket cover
• Cover gasket
• Bushing
• Mounting bolts

Installation Guide

1. Disconnect the battery and drain the outdrive cooling system to prevent water spillage during service.
2. Remove the lower unit from the upper gearcase following your MerCruiser service manual procedures.
3. Locate and remove the old water pocket cover by unscrewing the mounting bolts. Carefully extract the old water tube and bushing.
4. Clean all mating surfaces on the gearcase thoroughly, removing old gasket material and corrosion to ensure a proper seal.
5. Install the new bushing into the gearcase housing, ensuring it is properly seated.
6. Insert the new water tube through the bushing, aligning it with the housing channel.
7. Position the new gasket on the water pocket cover mounting surface.
8. Install the water pocket cover over the water tube, aligning the bolt holes with the gearcase.
9. Thread in the new mounting bolts and tighten in a cross-pattern to the torque specification listed in your service manual.
10. Reinstall the lower unit onto the upper gearcase, ensuring the water tube seats properly into the lower unit inlet.
11. Refill the outdrive with the appropriate gear lubricant and reconnect the battery.
12. Test the cooling system by running the engine with a flush attachment or in the water, checking for leaks around the water pocket cover.

Troubleshooting & FAQ

Q: How do I confirm this kit fits my specific Alpha One drive?
A: This kit is designed exclusively for Alpha One Generation 1 drives, including MerCruiser #1, R, and MR models. It will NOT fit Alpha One Generation II drives. Check your drive's serial number tag or consult your owner's manual to verify you have a Gen 1 unit before ordering.

Q: What are the signs that my water tube housing needs replacement?
A: Common symptoms include overheating, reduced water flow from the tell-tale outlet, visible corrosion or cracks in the water pocket cover, or coolant leaks around the gearcase area. If your engine runs hot despite proper impeller function, inspect this assembly.

Q: Can I reuse the old bolts and gasket?
A: No, it is strongly recommended to use the new gasket and bolts included in this kit. Reusing old gaskets can lead to leaks, and old bolts may have corrosion or stretched threads that compromise the seal and structural integrity.

Q: How often should this water tube housing be replaced?
A: Replace the water tube housing whenever you notice leaks, corrosion, or damage during routine maintenance. Inspect it annually during impeller changes or lower unit service, and replace as needed—typically every 3–5 years depending on operating conditions and exposure to saltwater.

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.