Gasket – Fits Mercury Marine Alpha One GEN II (Replaces Mercury Marine 27-988231)
Gasket – Fits Mercury Marine Alpha One GEN II (Replaces Mercury Marine 27-988231) 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.).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Gasket – Fits Mercury Marine Alpha One GEN II (Replaces Mercury Mar...
Product Details
This Gasket – Fits Mercury Marine Alpha One GEN II is designed for transom assemblies on Mercury Marine Alpha One GEN II (1991 and up), R/MR/Alpha One (1983–1990), and various Bravo and Blackhawk models. It provides a reliable seal for the P/T hose connector.
This part is a direct replacement for several OEM and aftermarket part numbers, including Mercury Marine 27-988231, Sierra 18-0388, and GLM 32500.
- Engineered for a precise fit on Mercruiser Alpha One Gen I & II and Bravo gimbal housings.
- Ensures a durable, leak-free seal for the power trim hose connection.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury Marine | 27-988231 |
| Mercruiser | 27-988231 |
| Mercruiser | 988231 |
| Mercruiser | 981853 |
| Mercruiser | 98823 |
| Sierra | 18-0388 |
| OMC | 0508613 |
| GLM | 32500 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This gasket is compatible with a wide range of Mercury Marine sterndrive and transom assembly models, including Alpha, Bravo, and Blackhawk series.
| Brand | Model | Years | OEM Part No. |
|---|---|---|---|
| Mercury Marine | Alpha One (GEN. II) | 1991–1995 | 27-988231 |
| Mercury Marine | Alpha One (GEN.II) | 1996–1997 | 27-988231 |
| Mercury Marine | Alpha One (GEN.II) | 1998 and up | 27-988231 |
| Mercury Marine | R/MR/Alpha One (Sterndrive) | 1983–1990 | 27-988231 |
| Mercury Marine | R/MR/Alpha One (Transom Assembly) | 1983–1990 | 27-988231 |
| Mercury Marine | Blackhawk | 1994–1995 | 27-988231 |
| Mercury Marine | Bravo | 0M100001–0W249999 | 27-988231 |
| Mercury Marine | Bravo One | 0W250000 & Up | 27-988231 |
| Mercury Marine | Bravo Drives | 0B664190–0F729999 | 27-988231 |
| Mercury Marine | Bravo Sterndrives | 0F730000–0M100000 | 27-988231 |
| Mercury Marine | Bravo Three | 0M100001–0W249999 | 27-988231 |
| Mercury Marine | Bravo Three | 0W250000 & Up | 27-988231 |
| Mercury Marine | Bravo Three | 0B664190–0F729999 | 27-988231 |
| Mercury Marine | Bravo Three | 0F730000–0M100000 | 27-988231 |
| Mercury Marine | Bravo Two | 0M100001–0W249999 | 27-988231 |
| Mercury Marine | Bravo Two | 0W250000 & Up | 27-988231 |
| Mercury Marine | Bravo Two | 0B664190–0F729999 | 27-988231 |
| Mercury Marine | Bravo Two | 0F730000–0M100000 | 27-988231 |
| Mercury Marine | Bravo X One | 0M100001–0W249999 | 27-988231 |
| Mercury Marine | Bravo X One | 0W250000 & Up | 27-988231 |
| Mercury Marine | Bravo X Three | 0M100001–0W249999 | 27-988231 |
| Mercury Marine | Bravo X Three | 0W250000 & Up | 27-988231 |
| Mercury Marine | Bravo X Two | 0M100001–0W249999 | 27-988231 |
| Mercury Marine | Bravo X Two | 0W250000 & Up | 27-988231 |
| Mercury Marine | Bravo XR One | 0W240000 & Up | 27-988231 |
| Mercury Marine | Bravo XR One | 0L914990–0W239999 | 27-988231 |
| Mercury Marine | Bravo XR Sportmaster | 0M906878 & Up | 27-988231 |
| Mercury Marine | Bravo XR Sportmaster | 0M052945–0M906877 | 27-988231 |
| Mercury Marine | Bravo XR Three | 0W240000 & Up | 27-988231 |
| Mercury Marine | Bravo XZ One | 0L914990–0M999999 | 27-988231 |
| Mercury Marine | Hi Performance Transom | 0W150003 & Up | 27-988231 |
| Mercury Marine | Integrated Transom | 0M052768 & Up | 27-988231 |
| Mercury Marine | Integrated Transom | All Thru 0M052767 | 27-988231 |
Technical Specs
- Product Type
- Gasket
- Application
- P/T Hose Connector Gasket
- Product Dimensions
- 5.13 x 4.0 x 1.13 inches
- Weight
- 0.16 ounces (0.0045 kg)
- Warranty
- No warranty on OEM replacement parts, but covered by our 1-year Sea Sierra warranty.
What’s in the Box
- 1 x Gasket (Replaces 27-988231 / 988231)
Installation Notes
- Disconnect the boat's battery and ensure the engine is off and cool.
- Place a drain pan under the work area to catch any residual hydraulic fluid.
- Carefully disconnect the power trim hose connector from the gimbal housing or transom assembly.
- Remove the old, worn gasket. Take care not to scratch the mating surfaces.
- Thoroughly clean both mating surfaces, removing all residue from the old gasket.
- Position the new gasket correctly onto the connector.
- Reconnect and tighten the hose connector to the manufacturer's specified torque. Do not overtighten.
- Reconnect the battery, top off any lost fluid, and cycle the trim system to check for leaks.
Troubleshooting & FAQ
How do I confirm this gasket fits my specific sterndrive?
Check the compatibility table on this page. Your model and year or serial number range should be listed. You can also match the OEM part number 27-988231 from your service manual.
What are the signs of a failing P/T hose gasket?
Common signs include visible hydraulic fluid leaks around the trim hose connector at the transom, a spongy or slow-responding trim system, or a frequent need to top off the trim fluid reservoir.
Can I reuse my old gasket?
No. Gaskets are single-use components designed to compress and create a seal. Once removed, they lose their sealing ability and should always be replaced with a new one to prevent leaks.
Is any sealant required with this gasket?
Generally, this type of gasket is designed to be installed dry. Applying sealant can sometimes interfere with its ability to seal properly. Always follow the specific instructions in your engine's service manual.
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.
Payment & Security
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