Manifold Engine Block Drain Plug Kit – Fits MerCruiser/Mercury Inboard Engines (Replaces 22-806608A02, Sierra 18-4226)
Manifold Engine Block Drain Plug Kit – Fits MerCruiser/Mercury Inboard Engines (Replaces 22-806608A02, Sierra 18-4226) is backordered and will ship as soon as it is back in stock.
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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).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Manifold Engine Block Drain Plug Kit – Fits MerCruiser/Mercury Inbo...
Product Details
This Manifold Engine Block Drain Plug Kit is designed for most MerCruiser and Mercury V6 and V8 inboard/stern drive applications with closed cooling systems. These wingnut-style plugs allow for easy, hand-tightened draining of the engine block and manifold, essential for winterization and maintenance.
This kit serves as a direct replacement for Sierra 18-4226, MerCruiser 22-806608A02 and 22-806608A1, GLM 13992, and Malloy 9-41203 and 9-41203-10.
- Features a hand-tightened wingnut design for tool-free installation.
- Constructed from durable blue nylon/plastic to resist corrosion.
- Each plug includes a new O-ring for a secure, leak-free seal.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| MerCruiser/Mercury | 22-806608A02 |
| MerCruiser/Mercury | 22-806608A1 |
| Sierra | 18-4226 |
| GLM | 13992 |
| Malloy | 9-41203 |
| Malloy | 9-41203-10 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
These plugs are compatible with a wide range of MerCruiser/Mercury engines that use center rise manifolds and closed cooling systems. Always verify that your engine requires OEM part number 22-806608A02 before ordering.
| Brand | Model | OEM Part No. | Notes |
|---|---|---|---|
| MerCruiser | V6 Engines | 22-806608A02 | For closed cooling systems |
| MerCruiser | V8 Engines | 22-806608A02 | For closed cooling systems |
| Mercury | Inboard/Stern Drives | 22-806608A02 | Compatible with center rise manifolds |
Technical Specs
- Product Type
- Manifold/Engine Block Drain Plug
- Installation
- Hand-tightened (wingnut style)
- Material
- Nylon/Plastic
- Color
- Blue
- Function
- Drains engine block and manifold in closed cooling systems
- Quantity
- 5 or 10 pieces (depending on package)
- Includes O-rings
- Yes
- Weight
- Approximately 0.03 kg (1.13 oz) per package of 5
- Warranty
- 90-day refund/replacement (Amazon seller warranty)
What’s in the Box
Package options vary by seller. You will receive one of the following:
- 5 x Manifold Engine Block Drain Plugs (Replaces 22-806608A02) & 5 x O-rings
- or
- 10 x Manifold Engine Block Drain Plugs (Replaces 22-806608A02) & 10 x O-rings
Installation Notes
Follow these general steps for installation. Always consult your engine's service manual for model-specific instructions.
- Ensure the engine has cooled completely before beginning.
- Locate the existing drain plugs on the engine block and/or exhaust manifolds.
- Place a suitable container below the plug to catch any draining fluid.
- Carefully unscrew the old plug by hand.
- Wipe the threaded area clean and inspect for debris or damage.
- Place the new O-ring onto the new drain plug.
- Thread the new plug into place and hand-tighten until snug. Do not overtighten, as this can damage the plug or threads.
Troubleshooting & FAQ
Will this fit my specific V6/V8 MerCruiser engine?
This plug fits a wide range of MerCruiser engines with closed cooling systems. The most reliable way to ensure a perfect match is to confirm that your existing part number is 22-806608A02 or one of the other listed cross-references.
How do I know if I have a closed cooling system?
A closed cooling system (also known as freshwater cooling) uses an enclosed coolant loop with a heat exchanger, similar to a car's radiator. You will typically see a heat exchanger and a coolant reservoir. Open cooling systems draw raw water directly into the engine block.
How often should these drain plugs be replaced?
It's best practice to inspect your drain plugs every season, especially during winterization. Replace them if you notice any signs of cracking, brittleness, stripping of the wingnut, or if the O-ring is flattened or cracked.
What are the signs of a failing drain plug?
Common signs of failure include visible coolant leakage around the plug area (even when tightened), difficulty getting the plug to thread in or tighten securely, or visible cracks and stress marks in the plastic body.
Is it normal for a small amount of water to drip after installation?
No, a properly installed plug with a new O-ring should create a leak-free seal. If you see drips, remove the plug and check that the O-ring is seated correctly and that the sealing surface on the engine is clean and free of nicks or debris.
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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