16951Q1 Brass Cooling Drain Plug for MerCruiser 1/4 NPT
16951Q1 Brass Cooling Drain Plug for MerCruiser 1/4 NPT is backordered and will ship as soon as it is back in stock.
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16951Q1 Brass Cooling Drain Plug for MerCruiser 1/4 NPT
16951Q1 Brass Cooling Drain Plug for MerCruiser 1/4 NPT is backordered and will ship as soon as it is back in stock.
SERDAMARINE / MARINE EXHAUST PARTS
16951Q1 Brass Cooling Drain Plug for MerCruiser 1/4 NPT
Aftermarket brass cooling-system drain plug referenced to Mercury 16951Q1 for compatible GM-based MerCruiser engine-block and manifold ports. It uses a 1/4-inch NPT thread; compare the original reference and port specification.
Configuration & Specifications
| Component Function | Cooling-system drain plug / bleed screw |
|---|---|
| Thread Specification | 1/4" NPT |
| Material | Brass |
| Installation Location | Compatible GM cylinder block or exhaust manifold cooling-system drain and bleed ports |
Engine Applications
- MerCruiser GM-based sterndrive or inboard engine block / manifold cooling-system drain or bleed port; 1/4-inch NPT, brass.
Reference Numbers
The numbers below are provided for part identification and cross-reference only; they do not establish manufacturer identity or guarantee interchangeability without matching port thread and location.
| Mercury / Mariner OEM References | 16951A1, 16951T1, 16951Q1, 22-16951Q1, 22-16951A1, 22-16951T1, 22-64426, 22-87238 |
|---|---|
| OMC OEM Reference | 379957 |
| Volvo Penta OEM Reference | 82745 |
| Aftermarket References | Sierra 18-4218; GLM 13993; RECMAR REC82745 |
| Alternate Packaging References | Sierra 18-4218D (display-packaged version of 18-4218); Sierra 18-3223-9 (separate bulk-pack reference). These packaging identifiers are for cross-reference only and do not define the packaging of this listing. |
Supplied Parts
- Brass cooling-system drain plug / bleed screw (1/4" NPT)
Service & Installation Notes
General service guidance only. Use the service manual for your exact engine and exhaust configuration.
- Shut down the engine, prevent accidental starting, and allow the engine block, manifold, and cooling water to cool completely before removing any drain plug.
- Remove the existing fitting and inspect the cylinder-block or manifold port threads for corrosion, rust scale, or debris that could block cooling-system drainage or damage the brass threads.
- Compare the removed plug with the replacement to verify the 1/4" NPT thread specification before threading it into the port by hand to avoid cross-threading.
- Tighten according to the engine manufacturer's service manual procedures and inspect the port for cooling-water leaks during initial operation; shut down and inspect if any leakage occurs.
The Serdamarine Approach
Exhaust parts need a configuration match. Serdamarine focuses on marine exhaust manifolds and their related service parts. Application details, connection requirements and public reference numbers are presented together to support part selection.
Questions Before Replacement
Can this plug be used for a 1/8" NPT or metric 10 × 1 drain port?
No. This fitting is machined specifically for a 1/4" NPT pipe thread port on compatible GM engine blocks and manifolds. It is not interchangeable with 1/8" NPT or 10 × 1 threaded drain fittings.
Does this fit lower-unit gearcase drain holes or water-flush ports?
No. Although cataloged alongside general drain hardware, this brass plug is intended only for engine-block and exhaust-manifold cooling-system bleed or drain ports using a 1/4" NPT thread, not lower-unit gear-oil drains or flush connectors.
What do the Sierra 18-4218D and 18-3223-9 references indicate?
Sierra 18-4218D is a display-packaged version of 18-4218, and Sierra 18-3223-9 is a bulk-pack reference for the same 1/4" NPT brass drain plug design. They are listed for part cross-reference only and do not represent a bulk package or complete valve kit for this product.
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