Gasket – Fits Mercury / Mariner 25-30 HP 2-Stroke Outboards (Replaces 27-161582)
Gasket – Fits Mercury / Mariner 25-30 HP 2-Stroke Outboards (Replaces 27-161582) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This aftermarket Gasket – Fits Mercury / Mariner 25-30 HP 2-Stroke Outboards is engineered for a precise fit on international models with serial numbers from 0N001875 through 0N055504 and from 0N055505 and up. It ensures a reliable seal for the gear housing assembly, preventing fluid leaks and protecting internal components.
This part serves as a direct interchange for Mercury OEM part number 27-161582.
- Installation Location: Gear Housing Assembly
- Fuel Compatibility: Designed for use with standard gasoline outboard engines.
- Quality: Manufactured to meet or exceed OEM specifications for durability and performance.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury | 27-161582 | OEM Reference |
Engine & Model Compatibility
Confirm your engine model and serial number range in the table below to ensure correct fitment.
For Mercury and Mariner owners, this gasket fits specific 2-cylinder, 2-stroke international models within the 25 HP to 30 HP range. Please pay close attention to the serial number breaks listed in the notes.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Mercury | 25 (2 CYL.) (International) | 25 | 2-Stroke | 27-161582 | Serial: 0N018456 THRU 0N055504, Belgium |
| Mercury | 25 (2 CYL.)(2-STROKE)(International) | 25 | 2-Stroke | 27-161582 | Serial: 0N055505 & Up, Belgium |
| Mercury | 25 Jet (2 CYL.)(2-STROKE)(International) | 25 | 2-Stroke | 27-161582 | Serial: 0N088578 & Up, Belgium |
| Mercury | 30 (2 CYL.) (International) | 30 | 2-Stroke | 27-161582 | Serial: 0N001875 THRU 0N055504, Belgium |
| Mercury | 30 (2 CYL.)(2-STROKE)(International) | 30 | 2-Stroke | 27-161582 | Serial: 0N055505 & Up, Belgium |
| Mercury | 30 (2 CYL.)(International) | 30 | 2-Stroke | 27-161582 | Serial: 0G575500 AND UP |
Technical Specs
- Product Type
- Gasket
- Installation
- Gear Housing Assembly
- Fuel Type
- Compatible with gasoline outboard engines
- Dimensions
- 14.5″ L x 10.5″ W x 1.0″ H
- Weight
- 0.007 kg (0.015 lb)
- Other Technical Attributes
- OEM factory part
What’s in the Box
- 1 x GASKET (Replaces 27-161582)
Installation Notes
- Safety First: Disconnect the battery and ensure the engine is in a stable, secure position before beginning work.
- Drain Gear Lube: Place a drain pan under the lower unit and remove the drain/fill screws to empty the gear lube.
- Remove Lower Unit: Unbolt the gearcase (lower unit) from the outboard's midsection. Keep track of all bolts and hardware.
- Remove Old Gasket: Carefully separate the components and remove the old gear housing gasket.
- Clean Mating Surfaces: Thoroughly clean both mating surfaces. Use a plastic scraper and an appropriate solvent to remove all old gasket material and sealant residue. Ensure the surfaces are smooth, clean, and dry.
- Install New Gasket: Position the new gasket correctly. Do not use any additional sealant unless specified by the engine manufacturer's service manual.
- Reassemble: Reattach the lower unit, torquing the bolts to the manufacturer's specifications in the correct sequence.
- Refill Gear Lube: Install the upper vent screw and pump new, recommended gear lube into the lower drain hole until it flows out of the vent. Reinstall both screws with new washers.
- Final Check: Check for any leaks around the seam after refilling.
Troubleshooting & FAQ
How do I confirm this gasket fits my specific engine?
This gasket is designed for Mercury/Mariner 25–30 HP 2-stroke international models. The most reliable way to confirm fitment is by checking your engine's serial number against the ranges listed in the compatibility table: 0N001875 through 0N055504 and 0N055505 and up.
What are the signs of a failed gear housing gasket?
The most common signs are water intrusion into the gear lube (giving it a milky, a coffee-colored appearance), visible oil leaks from the gearcase seam, or a failure to hold pressure during a pressure test.
Can I reuse my old gasket?
No. Gaskets are single-use components designed to crush and create a seal between two surfaces. Reusing an old gasket will almost certainly result in an improper seal, leading to leaks and potential damage to your engine.
When should this gasket be replaced?
This gasket should be replaced any time the gear housing is separated from the lower unit. This is commonly done during water pump impeller replacement or other internal gearcase service.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is 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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