Gear Housing Seal Kit – Fits Mercury/MerCruiser Alpha One Drives (Replaces 26-33144A2)

$45.99 $73.00

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Gear Housing Seal Kit – Fits Mercury/MerCruiser Alpha One Drives (Replaces 26-33144A2) is backordered and will ship as soon as it is back in stock.

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Product Details

This comprehensive Gear Housing Seal Kit is designed for various MerCruiser sterndrive models from 1978–1990, including 120/140, 165, 228, 260, 470/485, R/MR, Alpha One, and Alpha One SS drives. It provides the essential seals and gaskets needed to service the lower gearcase unit, preventing water intrusion and oil leaks.

This kit is a direct aftermarket replacement for Mercury/Quicksilver 26-33144A2, GLM 87510, Sierra 18-2652, and HSCJMEHT Alpha One Lower Seal Kit.

Application: Complete service kit for the lower unit/gear housing.
Installation: Includes seals for both the propeller shaft and driveshaft areas.
Compatibility: Engineered to fit a wide range of early MerCruiser R, MR, and Alpha One drives.

Part Number Matrix

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

Brand	Part Number
Mercury/Quicksilver	26-33144A2
GLM	87510
Sierra	18-2652
HSCJMEHT	Alpha One Lower Seal Kit

Engine & Model Compatibility

Confirm your engine model/year in the tables below.

For MerCruiser sterndrive and transom assembly models:

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
MerCruiser	120/140	120-140	4-Stroke	1978–1982	26-33144A2	Serial #4893635-6225576
MerCruiser	165	165	4-Stroke	1978–1981	26-33144A2	Serial #4890460 & up
MerCruiser	228	228	4-Stroke	1978–1982	26-33144A2	Serial #4898730-6225576
MerCruiser	260	260	4-Stroke	1978–1982	26-33144A2	Serial #4898730-6225576
MerCruiser	470	170	4-Stroke	1978–1982	26-33144A2	Serial #4893835-6225576
MerCruiser	485	185	4-Stroke	1980–1982	26-33144A2	Serial #4893835 & up
MerCruiser	898	228	4-Stroke	1978–1982	26-33144A2	Serial #4898730-6225576
MerCruiser	R/MR/Alpha One (Sterndrive)			1983–1990	26-33144A2	Serial #6225577-0F386995
MerCruiser	R/MR/Alpha One (Transom Assembly)			1983–1990	26-33144A2	Serial #6216687-0F386995
MerCruiser	Alpha One SS			1986–1989	26-33144A2	All serials
MerCruiser	SSM II/III/IV/V			1982–1995	26-33144A2	All serials

Technical Specs

Product Type: Gear Housing/Lower Unit Seal Kit
Installation: Propeller Shaft & Driveshaft Seals
Application: Lower Unit/Gear Housing
Weight: 0.28 lbs (0.127 kg)
Package Dimensions: 15.0" L x 14.0" W x 5.0" H
Other Technical Attributes: W9 Gear Housing Seal Kit

What’s in the Box

O-Ring (700-81160)
Gasket (700-31020)
Gasket (700-31010)
O-Ring 2.125 I.D. (700-82270)
Gasket (700-31050)
Seal (700-85140)
Seal (700-31170)
Slinger (700-21330)
Seal (700-12830)
O-Ring 2.188 I.D. (700-81390)
Oil Seal (700-85040)
Oil Seal (700-85070)
Gasket (700-30010)
Bushing Assembly (700-21010)
O-Ring (700-83445)
Oil Seal (inside) (700-85130)
Oil Seal (outside) (700-85700)

Installation Notes

Place the drive in the full-tilt position and drain the gear lube into a suitable container. Inspect the old lube for signs of water (milky) or metal shavings.
Remove the propeller assembly, taking care not to lose the thrust washer.
Unbolt and carefully separate the lower gearcase unit from the upper housing.
Systematically remove the old seals, gaskets, and o-rings from the driveshaft and propeller shaft housings. Use a seal puller to a-void scratching the housing surfaces.
Clean all sealing surfaces thoroughly, ensuring they are free of old gasket material, corrosion, or burrs.
Install the new seals using an appropriate seal driver or socket, ensuring they are seated evenly and at the correct depth. Lightly lubricate seals with 2-4-C grease.
Reassemble the gearcase unit, using the new gaskets and o-rings provided in the kit.
Torque all bolts to the manufacturer's specified values in the recommended sequence.
Refill the lower unit with high-quality marine gear lube to the proper level.
Reinstall the propeller and check for smooth operation before returning to the water.

Troubleshooting & FAQ

What are the signs my gear housing seals are failing?

Common indicators of seal failure include milky, creamy, or water-contaminated gear lube, visible oil slicks on the water surface around your drive, and a recurring need to top off the gear lube. Any of these symptoms warrant an inspection.

Is this kit for the upper or lower unit of the sterndrive?

This is a lower unit seal kit, specifically for the gear housing where the propeller shaft and driveshaft are located. It does not contain seals for the upper driveshaft housing.

Do I need special tools for installation?

Yes, proper installation requires specialized tools, including a seal puller, a seal driver set, and a torque wrench. Using the correct tools prevents damage to the new seals and the aluminum housing, ensuring a reliable, long-lasting repair.

How often should these seals be replaced?

We recommend inspecting the gear lube annually. As a preventative measure, seals should be considered for replacement every 2-3 years, especially in saltwater environments. They must be replaced immediately if any signs of a leak are found.

What is the difference between this and the OEM kit?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All parts are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency to ensure proper fit and function.

How much is shipping and how fast will it arrive?

We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free to most locations, with expedited options available at checkout where applicable.

What is the warranty and return policy?

This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window, provided the item is unused and in its original condition. See our policy page or reach out for instructions.

Safety & Important Info

Verify images and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement part, not an original equipment (OEM) component.
Professional installation is highly recommended for safety and optimal performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world reliability and performance.
Fast Global Fulfillment — We offer free standard delivery to most regions with an average transit time of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

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