Drain Screw Gasket – Fits Mercury/MerCruiser/Johnson/Evinrude Lower Unit (Replaces 12-19183)
Drain Screw Gasket – Fits Mercury/MerCruiser/Johnson/Evinrude Lower Unit (Replaces 12-19183) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Drain Screw Gasket – Fits Mercury/MerCruiser/Johnson/Evinrude Lower Unit (Replaces 12-19183) is backordered and will ship as soon as it is back in stock.
Product Details
This high-quality aftermarket Drain Screw Gasket – Fits Mercury/MerCruiser/Johnson/Evinrude Lower Unit (Replaces 12-19183) ensures a perfect seal for your marine engine's gearcase. It is designed for all MerCruiser stern drives and most Mercury/Mariner outboards that use a 3/8-16 drain or fill screw. It also fits Johnson/Evinrude outboards with the same 3/8-16 thread size, providing broad compatibility across popular engine brands.
This part offers a direct interchange for a wide array of part numbers from brands like Mercury, Johnson/Evinrude, Sierra, GLM, and Mallory. It is available in two designs: the traditional blue fiber style and a newer yellow, silicone-based rubber coated stainless steel version which does not require crushing to seal.
- Seals gearcase drain and fill screw holes to prevent water intrusion and oil leaks.
- Fits standard 3/8-16 threaded drain plugs.
- Available in both traditional blue fiber and modern yellow rubber-coated steel designs.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury/MerCruiser | 12-19183Q02, 12-19183K02, 12-191833, 191832, 19183, 19183B, 20260B, 20260 |
| Johnson/Evinrude | 307552, 300434 |
| Sierra | 18-2244, 18-2945, 18-29451-9 |
| GLM | 31170 |
| Mallory | 9-60101, 9-60102 |
| SEI Marine | 98-102-09 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury/MerCruiser, this gasket fits all stern drives and most outboard gearcases. Note that some newer FourStroke EFI, Verado, and Racing models use the yellow rubber-coated steel variant (OEM 26-830749).
For Johnson/Evinrude and Chrysler/Force/US Marine, this part fits all outboards equipped with 3/8-16 drain/fill screw holes.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| MerCruiser | All stern drives | All | All | All | 12-19183, 12-191832, 12-191833, 12-19183B, 12-20260, 12-20260B | Traditional blue gasket |
| Mercury | Most outboards | All | All | All | 12-19183, 12-191832, 12-191833, 12-20260 | Except Japanese origin outboards |
| Mercury | 40-50-60 EFI | 40-60 | 4-Stroke | All | 26-830749 | Yellow rubber coated stainless steel (newer design) |
| Mercury | 70-90 EFI | 70-90 | 4-Stroke | All | 26-830749 | Yellow rubber coated stainless steel (newer design) |
| Mercury | 115 EFI | 115 | 4-Stroke | All | 26-830749 | Yellow rubber coated stainless steel (newer design) |
| Mercury | 135-300 Verado | 135-300 | 4-Stroke | All | 26-830749 | Yellow rubber coated stainless steel (newer design) |
| Mercury | 175-300 Four Stroke V6 & V8 | 175-300 | 4-Stroke | All | 26-830749 | Yellow rubber coated stainless steel (newer design) |
| Mercury | 250-300 4.6L V8 Racing | 250-300 | 4-Stroke | All | 26-830749 | Yellow rubber coated stainless steel (newer design) |
| Mercury | 450 4.6L V8 Racing | 450 | 4-Stroke | All | 26-830749 | Yellow rubber coated stainless steel (newer design) |
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | Outboards | All | All | All | 307552, 300434 | Fits 3/8-16 drain/fill screw holes |
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Chrysler/Force/US Marine | Outboards | All | All | All | F50556, F8077, F8186 | Fits 3/8-16 drain/fill screw holes |
Technical Specs
- Product Type
- Drain Screw Gasket/Seal
- Installation
- Fits 3/8-16 drain/fill screw holes
- Housing Material
- Various (Blue fiber gasket or Yellow rubber coated stainless steel)
- Housing Color
- Blue (traditional) or Yellow (newer design)
- Thread Size
- 3/8-16
- Other Technical Attributes
- Newer yellow design is silicone-based and does not require crushing to form seal
What’s in the Box
- 1 x Drain Screw Gasket (12-19183Q02/12-19183K02)
Installation Notes
- Position the engine so the lower unit drain screw is pointing downwards. For outboards, tilt the engine up.
- Place a suitable oil drain pan under the lower unit.
- Using a large flathead screwdriver, loosen and remove the lower drain/fill screw. Be prepared for gear lube to start draining.
- Remove the upper (vent) screw to allow oil to drain completely.
- Inspect the magnetic tip of the drain screw for metal shavings, which can indicate gear wear.
- Remove and discard the old drain screw gasket. Clean the screw threads and the seating surface on the gearcase.
- Place the new gasket onto the drain screw.
- Once the gear lube has been refilled according to the manufacturer's procedure, reinstall the drain screw with the new gasket. Tighten until snug, but do not overtighten.
- Clean any excess oil and monitor the drain screw for leaks after running the engine.
Troubleshooting & FAQ
How do I know if I need the blue or yellow gasket?
Both the traditional blue fiber gasket and the newer yellow rubber-coated steel gasket fit the same 3/8-16 drain screw. The yellow design was introduced on some Mercury models from the mid-2000s onwards and offers a more modern seal. For most applications, either style works, but it is best to match the type originally used on your engine if possible.
Will this gasket fit my Japanese-made Mercury outboard?
No. Most Mercury outboards manufactured by Yamaha or Tohatsu (which are typically smaller horsepower models) use a different, metric drain screw and gasket. This 3/8-16 gasket is for US-made Mercury/Mariner models and all MerCruiser stern drives.
Does the newer yellow gasket require a different installation torque?
The yellow silicone-based gasket does not require "crushing" to form a seal like the traditional blue fiber one. It should be tightened until it is snug and secure. Overtightening can damage the gasket or the gearcase threads. Always follow the torque specs in your service manual if available.
How often should I replace my drain screw gasket?
The drain screw gasket should be replaced every time you change your lower unit gear lube, which is typically recommended annually or every 100 hours of operation, whichever comes first. Reusing old gaskets significantly increases the risk of leaks.
What are the signs of a failing drain screw gasket?
The most common signs are gear lube weeping or dripping from the drain screw area. Another critical sign is milky, emulsified gear lube when you drain it, which indicates water has entered the lower unit—often due to a failed gasket.
Can I reuse my old drain screw gasket?
No, it is strongly recommended to use a new gasket every time the drain screw is removed. The old gasket has been compressed and may have imperfections or nicks that prevent it from creating a perfect seal, leading to oil leaks or water intrusion.
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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