Gearcase Seal Kit – Fits Mercury/Mariner/Force 8-25 HP (Replaces 26-85090A2)

$65.99

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Product Details

This comprehensive Gearcase Seal Kit – Fits Mercury/Mariner/Force 8-25 HP (Replaces 26-85090A2) is engineered to restore the lower unit sealing integrity on a wide range of outboard motors. It is designed for Mercury/Mariner/Force models from 8 HP to 25 HP (2-Stroke & 4-Stroke) manufactured between 1984 and 2006, as well as Chrysler/Force 25 HP 2-Stroke engines from 1996 to 1998.

It serves as a direct replacement for multiple part numbers, including Mercury 26-85090A2, Sierra 18-2624, GLM 87808, Mallory 9-74205, and SEI 95-262-11AK, ensuring a precise fit and reliable performance.

Engineered for direct replacement installation.
Prevents water intrusion and oil leaks in the gearcase/lower unit.
Includes all necessary seals, gaskets, and O-rings for a complete service.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Mercury	26-85090A2
Sierra	18-2624
GLM	87808
Mallory	9-74205
SEI	95-262-11AK
Automotive Authority	18-2624

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Fitment for Mercury, Mariner, and Force models. Serial numbers are critical for confirming compatibility.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury	8	8	4-Stroke	1999–2006	26-85090A2	Serial: 0P086824–0P400999
Mercury	9.9	9.9	4-Stroke	1999–2006	26-85090A2	Serial: 0G760300–1B226999, 0P075166–0P400999
Mercury	13.5	13.5	4-Stroke	1999–2006	26-85090A2	Serial: 0P134638–0P400999, 0P401000 & Up (International)
Mercury	15	15	4-Stroke	1998–2006	26-85090A2	Serial: 9973100–0P016999, 0G590000–0G760299, 0G760300–1B226999, 0P075166–0P400999, 1B227000–1B727495, 0P401000 & Up
Mercury	15 Marathon XD	15	2-Stroke	1999–2006	26-85090A2	Serial: 9927000–0P016999, 0P017000–0P325499
Mercury	15 Sea Pro (XD)	15	2-Stroke	1999–2006	26-85090A2	Serial: 9927000–0P016999, 0P017000–0P325499
Mercury	18XD	18	2-Stroke	1984–1999	26-85090A2	Serial: 6443973–0B238463, 7209533–0A730006, 9378151–9507380
Mercury	20	20	2-Stroke	1995–2006	26-85090A2	Serial: 9507381–9807908, 9807909–0P016999, 0A730007 & Up, 0B238464–0G044026, 0G044027–0G760299, 0G760300–0T979999, 0P017000–0P325499, 0P325500 & Up
Mercury	20 Jet	20	2-Stroke	1995–2006	26-85090A2	Serial: 9807909–0P016999, 0G044027–0G760299, 0G760300–0T979999, 0T980000–0T999999, 1B000001 & Up, 0P017000–0P325499
Mercury	20XD	20	2-Stroke	1984–1995	26-85090A2	Serial: 6443973–0B238463, 7209533–0A730006, 9415101–9507380
Mercury	25	25	2-Stroke	1996–2006	26-85090A2	Serial: 0T980000–0T999999, 1B000001 & Up, 0P325500 & Up
Mercury	25, 25 Marathon, Super 15	25	2-Stroke	1995–2006	26-85090A2	Serial: 9507381–9807908, 9807909–0P016999, 0A730007 & Up, 0B238464–0G044026, 0G044027–0G760299, 0G760300–0T979999, 0P017000–0P325499
Mercury	25, 25 Sea Pro, Super 15	25	2-Stroke	1995–2006	26-85090A2	Serial: 9507381–9807908, 9807909–0P016999, 0A730007 & Up, 0B238464–0G044026, 0G044027–0G760299, 0G760300–0T979999, 0P017000–0P325499
Mercury	25XD	25	2-Stroke	1984–1995	26-85090A2	Serial: 6443973–0B238463, 7209533–0A730006, 9415101–9507380
Mercury	25 Lightning	25	2-Stroke	1996–1997	26-85090A2	Serial: 0E268781–0E287999, International Only
Force	25	25	2-Stroke	1996	26-85090A2	Serial: 225.582500, 0E127700–0E202999
Force	25	25	2-Stroke	1997	26-85090A2	Serial: 225.582500, 0E203000–0E287999
Force	25	25	2-Stroke	1998	26-85090A2	Serial: 0E288000–0E344999
Force	25 w/ 6.6 Gallon Remote Tank	25	2-Stroke	1997	26-85090A2	Serial: 225.582501, 225.582591
Force	25 w/ 6.6 Gallon Remote Tank	25	2-Stroke	1998	26-85090A2	Serial: 225.592500, 225.592590

Technical Specs

Product Type: Lower Unit Gearcase Seal Kit
Installation: Direct replacement
Weight: 0.13 kg (0.29 lbs)
Dimensions: 7.13" H x 6.0" W x 1.0" L
Other Technical Attributes: For gearcase/lower unit sealing applications

What’s in the Box

1 x Oil Seal (18-0579)
1 x Oil Seal (18-0580)
2 x Oil Seal (18-0586)
2 x Impeller Washer Gasket (18-2560)
1 x Impeller Gasket (18-2562)
1 x Shift Shaft Boot (18-2742)
2 x Drain Screw Gasket (18-2945)
1 x O-Ring (18-7100)
1 x O-Ring (18-7135)
2 x O-Ring (18-7188)
1 x O-Ring (18-7419)
1 x O-Ring Pkg of 5 (18-7956)

Installation Notes

Professional installation is highly recommended. The process involves draining the gear lube, removing the lower unit assembly, and methodically disassembling the gearcase to access and replace each seal and gasket. Ensure all mating surfaces are meticulously cleaned and appropriately lubricated before reassembly. Always consult your engine’s official service manual for detailed step-by-step instructions, torque specifications, and required specialized tools.

Troubleshooting & FAQ

How do I know if my gearcase seals are failing?

The most common signs of a failing gearcase seal are water intrusion into the gear oil (giving it a milky, cloudy appearance) or visible oil leaks around the propeller shaft, driveshaft, or shift shaft. Regular gear lube inspection is key to early detection.

Is this kit compatible with my specific serial number?

This kit fits a wide range of serial numbers for Mercury, Mariner, and Force engines from 8 to 25 HP. It is crucial to check the detailed compatibility table on this page to confirm a match with your engine's model, year, and specific serial number range before ordering.

Do I need special tools for this installation?

Yes, proper installation may require specialized tools such as a seal puller, a bearing carrier retainer wrench, and a press to install seals without causing damage. Using the correct tools ensures a secure fit and prevents premature failure.

What is the recommended replacement interval for gearcase seals?

It is recommended to inspect your gear lube at least once a year or every 100 hours of operation. Seals should be replaced as a preventative measure whenever the lower unit is being serviced or immediately if any signs of leakage or water contamination are found.

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

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