Lower Unit Drain Plug Gaskets for Mercury, Mariner and MerCruiser — Replaces 12-19183-3, 12-19183Q02
Lower Unit Drain Plug Gaskets for Mercury, Mariner and MerCruiser — Replaces 12-19183-3, 12-19183Q02 is backordered and will ship as soon as it is back in stock.
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Lower Unit Drain Plug Gaskets for Mercury, Mariner and MerCruiser —...
Lower Unit Drain Plug Gaskets for Mercury, Mariner and MerCruiser — Replaces 12-19183-3, 12-19183Q02 is backordered and will ship as soon as it is back in stock.
Product Details
These lower unit drain plug gaskets are replacement sealing washers for compatible Mercury and Mariner outboard engines and MerCruiser sterndrives. They are used on drain and fill screws with the applicable 3/8-16 thread size to help prevent gear-lube leakage during normal lower-unit service.
Replacement references associated with this gasket style include Mercury 12-19183-3, 12-19183Q02 and 12-19183K02, along with selected aftermarket references listed below. Confirm the part number, gasket dimensions and drain-screw application before ordering.
- Application: Lower-unit drain and fill screw sealing.
- Thread application: Intended for compatible 3/8-16 drain and fill screw holes.
- Service recommendation: Replace the gasket whenever the drain or fill screw is removed, especially during a gear-lube change.
- Aftermarket replacement: This is a replacement part, not a Mercury OEM component.
Part Number Matrix
The following references are commonly associated with this replacement gasket style. Part-number interchange does not replace verification of the exact screw, dimensions or application.
| Brand | Part Number |
|---|---|
| Mercury | 12-19183-3 |
| Mercury | 12-19183Q02 |
| Mercury | 12-19183K02 |
| Sierra | 18-2244 |
| Sierra | 18-2245 |
| SEI Marine | 98-102-09 |
| Mallory | 9-60101 |
| Mallory | 9-60102 |
| GLM | 31170 |
| OBR Red Rhino | MR-103 |
Engine and Model Compatibility
Compatibility depends on the lower-unit design and drain-screw specification, not solely on the engine brand or horsepower. Verify that your unit uses the applicable 3/8-16 drain and fill screws and that the replacement gasket matches the original part before installation.
| Brand | Application | Rated HP | Stroke | Reference Part No. | Fitment Condition |
|---|---|---|---|---|---|
| Mercury | Compatible MerCruiser sterndrives | Various | Various | 12-19183-3 | Must use the applicable 3/8-16 drain/fill screw and matching gasket. |
| Mercury/Mariner | Compatible outboard lower units | Various | 2-Stroke or 4-Stroke | 12-19183-3 | Verify the original gasket and drain-screw application before ordering. |
Technical Specifications
- Product Type
- Lower-unit drain plug gasket/sealing washer
- Primary Application
- Compatible drain and fill screws on selected Mercury, Mariner and MerCruiser lower units
- Thread Application
- 3/8-16 drain and fill screw holes, where specified by the engine or sterndrive
- Replacement Reference
- Mercury 12-19183-3, 12-19183Q02 and 12-19183K02
- Material
- Replacement sealing material; exact material and color may vary by manufacturer or supply variant
- Color
- May vary by supplier and production batch
- Service Use
- Replace after removal or during each applicable gear-lube service
- Brand Status
- Aftermarket replacement; not an OEM Mercury component
What's in the Box
Gaskets are supplied according to the package quantity shown for the selected product option. Package quantity may vary by supplier or variant. Confirm the quantity displayed with the offer before purchase.
Installation Notes
- Turn off the engine, allow it to cool and place a suitable drain pan below the lower unit.
- Remove the lower drain screw and then the upper vent or level screw, following the manufacturer's service procedure.
- Allow the gear lubricant to drain completely. Inspect the magnetic drain screw for unusual metal particles.
- Clean the screw and sealing surface. Remove and discard the old gasket.
- Install the replacement gasket on the drain or fill screw.
- Refill the lower unit with the manufacturer-specified gear lubricant through the appropriate fill opening.
- Reinstall the screws in the order recommended by the manufacturer. Use new gaskets on every screw where required.
- Tighten the screws to the manufacturer's specified torque. Do not overtighten.
- Clean the area and check for leakage after servicing.
Troubleshooting and FAQ
How do I confirm that this gasket fits my engine?
Match the old gasket or its part number with the references in the Part Number Matrix, then confirm that your lower unit uses the applicable 3/8-16 drain and fill screws. Engine model, year, serial number and lower-unit configuration can affect fitment.
Can I reuse the old drain plug gasket?
Replacement is recommended whenever the drain or fill screw is removed. A used gasket may already be compressed, hardened or damaged and may not seal reliably.
The replacement gasket is a different color from the original. Is that acceptable?
Color can vary by manufacturer and production batch. Verify the part number, dimensions and application rather than relying on color alone.
What are the signs of a leaking drain screw gasket?
Possible signs include gear oil around the drain screw, oil on the lower unit or skeg, a visible sheen on the water, or a lower-than-expected gear-lube level. Stop and investigate any suspected leak before continued operation.
What happens if the drain screw is overtightened?
Overtightening can damage the gasket, strip threads or crack the gearcase. Follow the manufacturer's torque specification and use a calibrated torque wrench when required.
Is this an OEM part?
No. This listing is for an aftermarket replacement gasket. The listed manufacturer part numbers are reference numbers used to help identify the application and are not a claim that this product is manufactured by Mercury, Mariner, Sierra, Mallory, GLM, SEI Marine or OBR Red Rhino.
Safety and Important Information
- Verify the part number, dimensions, drain-screw thread and lower-unit application before purchase.
- Keep model, year, serial-number and lower-unit conditions together when checking fitment.
- Use the manufacturer's service procedure and lubricant specification for your engine or sterndrive.
- Do not operate the unit if a gear-lube leak is present.
- Professional installation is recommended if you are not familiar with lower-unit service.
About Sea Sierra
- Marine Replacement Parts — Practical replacement components for routine service and maintenance.
- Fitment-Focused Listings — Reference numbers and application information are provided to help you compare your original part.
- Service Support — Review the product information and your engine documentation before installation.
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