Seal Kit – Fits MerCruiser Alpha One Gen II (Replaces 26-88397A1)

$35.80

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Product Details

This Seal Kit – Fits MerCruiser Alpha One Gen II (Replaces 26-88397A1) is specifically designed for MerCruiser Alpha One Gen II sterndrives from 1991 and newer, including models produced from 2004 onwards. It provides all the necessary seals and O-rings for servicing the upper driveshaft housing.

It serves as a direct aftermarket replacement for OEM part number 26-88397A1.

Installation Location: Engine Mount
Housing Material: Metal Alloy (for aftermarket versions)
Includes a comprehensive set of seals and O-rings for a complete repair.

Part Number Matrix

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

Brand	Part Number
MerCruiser	26-88397A1

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This kit is designed for the following MerCruiser models.

Brand	Model	Years	OEM Part No.
MerCruiser	Alpha One Gen II	1991–1995 (0D469859 Thru 0F679999)	26-88397A1
MerCruiser	Alpha One Gen II	1996–1997 (0F680000 Thru 0K999999)	26-88397A1
MerCruiser	Alpha One Gen II	1998 and up (0L100040 & up)	26-88397A1
MerCruiser	Alpha One Gen II	2004 and newer	26-88397A1

Technical Specs

Product Type: Driveshaft Housing Seal Kit
Installation: Engine Mount
Housing Material: Metal Alloy (for aftermarket versions)
Weight: 0.06 kg (0.13 lbs)
Product Dimensions: 14.0" L x 12.0" W x 7.0" H

What’s in the Box

1 x Oil Seal (18-2003)
2 x Oil Seal (18-2056)
1 x Check Valve Kit (18-2715)
1 x Seal Ring Gasket (18-2944)
1 x Drain Screw Gasket (18-2945)
1 x Double Lip Seal (18-3289)
2 x O Ring (18-7103)
1 x O Ring (18-7117)
1 x O Ring (18-7161)
1 x O Ring (18-7169)
1 x O Ring (18-7188)
2 x O Ring (18-7420)

Installation Notes

Always disconnect the battery before starting any repair work.
Properly drain the gear lube from the sterndrive unit.
Carefully remove the upper sterndrive unit following the manufacturer's service manual.
Disassemble the driveshaft housing to access the old seals.
Remove all old seals, gaskets, and O-rings, taking care not to scratch any metal surfaces.
Thoroughly clean all components and mating surfaces of any old sealant or debris.
Lightly lubricate the new seals and O-rings with marine grease before installation.
Install the new components, ensuring they are seated correctly and are not damaged.
Reassemble the driveshaft housing and sterndrive unit, torquing all fasteners to the specified values.
Refill the sterndrive with fresh, high-quality gear lube.
After reassembly, run the engine and check for any signs of leaks.

Troubleshooting & FAQ

Which MerCruiser models does this seal kit fit?

This kit is engineered for MerCruiser Alpha One Gen II sterndrives manufactured from 1991 to the present day, providing a wide range of coverage.

What are the signs that my driveshaft seals are failing?

Common indicators of a worn seal include finding water in the gear lube (which gives it a milky white appearance), observing oil leaking from the drive unit, or seeing an oil sheen on the water surface around your boat.

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

This is a complete upper driveshaft housing seal kit, intended to service the seals in the upper portion of the Alpha One Gen II sterndrive.

How can I confirm this kit will fit my specific sterndrive by its serial number?

This kit is confirmed to fit MerCruiser Alpha One Gen II models within these serial number ranges: 1991–1995 (0D469859–0F679999), 1996–1997 (0F680000–0K999999), and 1998 and newer (0L100040 and up). Always cross-reference your OEM part number (26-88397A1) to be certain.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials, and manufactured in an ISO 9002 facility and batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free; expedited options will appear at checkout where available.

Warranty & returns

This product is covered by a 1-year warranty against manufacturing defects under normal use. If any issues arise, please contact support 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. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement part, 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 quality control.

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