Water Pump Plate Gasket – Fits Mercury Mariner 9.9-25 HP Outboards (Replaces 27-993261, 99326)
Water Pump Plate Gasket – Fits Mercury Mariner 9.9-25 HP Outboards (Replaces 27-993261, 99326) is backordered and will ship as soon as it is back in stock.
Couldn't load pickup availability
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
Water Pump Plate Gasket – Fits Mercury Mariner 9.9-25 HP Outboards ...
Product Details
This Water Pump Plate Gasket is designed for a wide range of Mercury Marine and Mariner outboard engines from 9.9 to 25 HP, covering both 2-stroke and 4-stroke models manufactured from 1977 to the present. It ensures a proper seal between the water pump housing and the plate, which is critical for cooling system performance.
It serves as a direct interchange for multiple OEM and aftermarket part numbers, including Mercury 27-993261, 99326, and 85087, as well as GLM Marine 32360 and EMP 27-01614 / 27-00658.
- Installs between the water pump housing and wear plate.
- Essential for preventing leaks in the lower unit water pump assembly.
- Made from durable, high-quality composite gasket material to ensure a reliable seal.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 27-993261 |
| Mercury | 99326 |
| Mercury | 85087 |
| EMP | 27-01614 |
| EMP | 27-00658 |
| GLM Marine | 32360 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury, Mariner, and Force models, check your engine’s serial number against the ranges listed to ensure a precise match.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury | 9.9 (4-Stroke) (323 cc) | 9.9 | 4-Stroke | 1995–present | 27-993261 | Serial 0G760300 thru 1B226999 |
| Mercury | 9.9 (4-Stroke) (323 cc) | 9.9 | 4-Stroke | 1995–present | 27-993261 | Serial 0P075166 thru 0P400999 |
| Mercury | 13.5 (4-Stroke) (International) | 13.5 | 4-Stroke | 1995–present | 27-993261 | Serial 0P134638 thru 0P400999 |
| Mercury | 13.5 (4-Stroke) (International) | 13.5 | 4-Stroke | 2011–present | 27-993261 | Serial 0P401000 & Up |
| Mercury | 15 (4-Stroke) | 15 | 4-Stroke | 1993–1995 | 27-993261 | Serial 9973100 thru 0P016999 |
| Mercury | 15 (4-Stroke) | 15 | 4-Stroke | 1995–present | 27-993261 | Serial 0G590000 thru 0G760299 |
| Mercury | 15 (4-Stroke) | 15 | 4-Stroke | 1995–present | 27-993261 | Serial 0G760300 thru 1B226999 |
| Mercury | 15 (4-Stroke) | 15 | 4-Stroke | 1995–present | 27-993261 | Serial 0P075166 thru 0P400999 |
| Mercury | 15 (4-Stroke) | 15 | 4-Stroke | 2011–present | 27-993261 | Serial 0P401000 & Up |
| Mercury | 15 (4-Stroke) | 15 | 4-Stroke | 2011–present | 27-993261 | Serial 1B227000 thru 1B727495 |
| Mercury | 15 MARATHON XD | 15 | 2-Stroke | 1993–1995 | 27-993261 | Serial 9927000 thru 0P016999 |
| Mercury | 15 MARATHON XD | 15 | 2-Stroke | 1995–1997 | 27-993261 | Serial 0P017000 thru 0P325499 |
| Mercury | 15 SEA PRO (XD) | 15 | 2-Stroke | 1993–1995 | 27-993261 | Serial 9927000 thru 0P016999 |
| Mercury | 15 SEA PRO (XD) | 15 | 2-Stroke | 1995–1997 | 27-993261 | Serial 0P017000 thru 0P325499 |
| Mercury | 20 (2 CYL.) | 20 | 2-Stroke | 1977–1990 | 27-993261 | Multiple serial ranges |
| Mercury | 20 (2 CYL.) | 20 | 2-Stroke | 1990–1993 | 27-993261 | Serial 9507381 thru 9807908 |
| Mercury | 20 (2 CYL.) | 20 | 2-Stroke | 1993–1995 | 27-993261 | Serial 9807909 thru 0P016999 |
| Mercury | 20 (2 CYL.) | 20 | 2-Stroke | 1995–1997 | 27-993261 | Serial 0P017000 thru 0P325499 |
| Mercury | 20 (2 CYL.) | 20 | 2-Stroke | 1997–present | 27-993261 | Serial 0P325500 & Up |
| Mercury | 20 (2 CYL.) | 20 | 2-Stroke | 1995–1998 | 27-993261 | Serial 0G760300 thru 0T979999 |
| Mercury | 20 JET | 20 | 2-Stroke | 1993–1995 | 27-993261 | Serial 9807909 thru 0P016999 |
| Mercury | 20 JET | 20 | 2-Stroke | 1995–1997 | 27-993261 | Serial 0P017000 thru 0P325499 |
| Mercury | 20 JET | 20 | 2-Stroke | 1995–1998 | 27-993261 | Serial 0G760300 thru 0T979999 |
| Mercury | 20 JET | 20 | 2-Stroke | 1998–present | 27-993261 | Serial 0T980000 thru 0T999999, 1B000001 & Up |
| Mercury | 25 (2 CYL.) | 25 | 2-Stroke | 1997–present | 27-993261 | Serial 0P325500 & Up |
| Mercury | 25 (2 CYL.) | 25 | 2-Stroke | 1998–present | 27-993261 | Serial 0T980000 thru 0T999999, 1B000001 & Up |
| Mercury | 25 HP (1996-1998) | 25 | 2-Stroke | 1996–1998 | 27-993261 | Various serial ranges |
| Mercury | 25 H.P. LIGHTNING (3 CYL.) (INTL. ONLY) | 25 | 2-Stroke | 1995–1997 | 27-993261 | Serial 0E268781 thru 0E287999 |
| Mercury | 25, 25 MARATHON, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1990–1993 | 27-993261 | Serial 9507381 thru 9807908 |
| Mercury | 25, 25 MARATHON, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1993–1995 | 27-993261 | Serial 9807909 thru 0P016999 |
| Mercury | 25, 25 MARATHON, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1995–1997 | 27-993261 | Serial 0P017000 thru 0P325499 |
| Mercury | 25, 25 MARATHON, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1995–1998 | 27-993261 | Serial 0G760300 thru 0T979999 |
| Mercury | 25, 25 SEA PRO, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1990–1993 | 27-993261 | Serial 9507381 thru 9807908 |
| Mercury | 25, 25 SEA PRO, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1993–1995 | 27-993261 | Serial 9807909 thru 0P016999 |
| Mercury | 25, 25 SEA PRO, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1995–1997 | 27-993261 | Serial 0P017000 thru 0P325499 |
| Mercury | 25, 25 SEA PRO, SUPER 15 (2 CYL.) | 25 | 2-Stroke | 1995–1998 | 27-993261 | Serial 0G760300 thru 0T979999 |
| Mariner | 20 (2 CYL.) | 20 | 2-Stroke | 1977–1987 | 27-993261 | Multiple serial ranges |
| Mariner | 25 (2 CYL.) | 25 | 2-Stroke | 1985–1987 | 27-993261 | Multiple serial ranges |
| Force | 25 H.P. (1996-1998) | 25 | 2-Stroke | 1996–1998 | 27-993261 | Various serial ranges |
Technical Specs
- Product Type
- Water Pump Plate Gasket
- Application
- Lower unit water pump assembly
- Material
- Gasket material (paper/composite)
- Dimensions
- 6.0 × 7.5 × 1.25 in (approx. 15.2 × 19.1 × 3.2 cm)
- Weight
- 0.014 kg (0.03 lb)
What’s in the Box
- 1 x Water Pump Plate Gasket (Replaces 27-993261)
Installation Notes
- Disconnect the battery and ensure the engine is off and in neutral.
- Position a drain pan and remove the gearcase drain screw to empty the lower unit oil.
- Remove the mounting bolts securing the lower unit (gearcase) to the engine's upper assembly.
- Carefully lower the gearcase to access the water pump housing. You may need to disconnect the shift shaft.
- Disassemble the water pump, noting the order of all components. Remove the old plate gasket and clean both mating surfaces thoroughly.
- Install the new water pump plate gasket, ensuring it is seated correctly on the locating dowels.
- Reassemble the water pump components and secure the housing.
- Reinstall the lower unit, refill with appropriate gear lube, and test the engine's cooling system function at idle.
Troubleshooting & FAQ
How do I know if my water pump gasket is failing?
Signs of a failing gasket include the engine overheating at idle or low speeds, a weak or inconsistent water stream from the "tell-tale" outlet, or finding water mixed in with your gearcase oil during a change, which can indicate a seal failure.
Is this the only part I need for a water pump service?
No. This is only the plate gasket. A complete water pump service typically requires a full kit, which includes the impeller, wear plate, housing, face plate, and other seals or gaskets. Replacing only one gasket may not resolve underlying issues.
How often should I replace my water pump components?
For preventative maintenance, it is recommended to service your water pump (including the impeller and all gaskets) every 1-2 years or every 100-200 hours of operation, whichever comes first, especially if you operate in saltwater or sandy conditions.
Can I reuse my old gasket if it looks okay?
No. Gaskets are single-use components designed to compress and create a seal. Once removed, they lose their sealing ability and will almost certainly cause leaks if reused, leading to potential engine damage from overheating.
My engine model is not listed, but the part looks identical. Will it fit?
We strongly advise against using a part if your specific engine model, year, and serial number are not listed in our compatibility table. Minor differences that are not visible can lead to improper fitment and engine damage. Always verify the OEM part number first.
What are the signs of a worn-out impeller vs. a bad gasket?
A worn impeller typically causes a gradual loss of cooling performance (weak tell-tale stream). A failed gasket can cause a sudden loss of water pressure, an external water leak from the gearcase seam, or water intrusion into the gear lube.
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
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
