Lower Unit Seal Kit for Tohatsu, Mercury and Nissan 4–6 HP Outboards — Replaces 369-87321-0
Lower Unit Seal Kit for Tohatsu, Mercury and Nissan 4–6 HP Outboards — Replaces 369-87321-0 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
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Lower Unit Seal Kit for Tohatsu, Mercury and Nissan 4–6 HP Outboard...
Lower Unit Seal Kit for Tohatsu, Mercury and Nissan 4–6 HP Outboards — Replaces 369-87321-0 is backordered and will ship as soon as it is back in stock.
Product Details
This lower unit seal kit is designed for servicing the gearcase and water-pump sealing points on selected Tohatsu, Nissan and Mercury 4–6 HP outboards. It is listed for Tohatsu and Nissan 2-stroke M5B/NS5B models and 4-stroke MFS4/MFS5/MFS6 and NSF4/NSF5/NSF6 models, as well as selected Mercury F4, F5 and F6 4-stroke outboards. Confirm the exact model, year and original part number before ordering.
The kit is intended as an aftermarket replacement for the following listed references: Tohatsu/Nissan 369-87321-0, 369873210, 369873210M and 369873212M; and Mercury 27-8M0155392, 95220A2, 27-8M0134073, 8M0082882 and 27-8M0188431.
- Product type: Lower unit and gearcase seal kit
- Installation: Replacement seals, O-rings and gaskets for compatible applications
- Materials: Non-asbestos paper gaskets, rubber O-rings and synthetic seals
- Service use: Lower unit, gearcase and water-pump sealing service
Part Number Matrix
Use this matrix to compare the listed OEM and aftermarket reference numbers with the part removed from your engine.
| Brand | Part Number | Superseded By | Notes |
|---|---|---|---|
| Tohatsu/Nissan | 369-87321-0 / 369873210 / 369873210M | 369873212M | Listed replacement and superseding references. |
| Mercury | 27-8M0155392 / 95220A2 / 27-8M0134073 / 8M0082882 / 27-8M0188431 | Listed cross-references for compatible applications. |
Engine & Model Compatibility
The applications below reflect the listed model and year information. Model generations and part numbers can vary, so compare your engine identification label and removed parts before installation.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Tohatsu | M5B | 5 | 2-Stroke | 2003 | 369-87321-0 | Verify model identification before ordering. |
| Nissan | NS5B | 5 | 2-Stroke | 2003 | 369-87321-0 | Verify model identification before ordering. |
| Tohatsu | MFS4A2, MFS5A2, MFS6A2 | 4, 5, 6 | 4-Stroke | 2002 | 369-87321-0 | |
| Nissan | NSF4A2, NSF5A2, NSF6A2 | 4, 5, 6 | 4-Stroke | 2002 | 369-87321-0 | |
| Tohatsu | MFS4B, MFS5B, MFS6B | 4, 5, 6 | 4-Stroke | 2005–2010 | 369-87321-0 | |
| Nissan | NSF4B, NSF5B, NSF6B | 4, 5, 6 | 4-Stroke | 2005–2010 | 369-87321-0 | |
| Tohatsu | MFS4C, MFS5C, MFS6C | 4, 5, 6 | 4-Stroke | 2011–2014 | 369-87321-0 | |
| Nissan | NSF4C, NSF5C, NSF6C | 4, 5, 6 | 4-Stroke | 2011–2014 | 369-87321-0 | |
| Mercury | F4, F5, F6 | 4, 5, 6 | 4-Stroke | Not specified | 27-8M0155392, 95220A2 | Confirm the exact model and original part number. |
Technical Specs
- Product Type
- Lower Unit Seal Kit
- Installation
- Replacement installation for compatible applications
- Fuel Type
- Gasoline outboard applications
- Materials
- Non-asbestos paper gaskets, rubber O-rings and synthetic seals
- Kit Contents
- Nine replacement gaskets, seals and O-rings as listed below
- Product Status
- Aftermarket replacement, not an OEM component
What’s in the Box
- 1 × Gasket (332-60006-0)
- 1 × Oil Seal (369-60111-0)
- 1 × O-Ring (345-65015-0)
- 1 × Upper Pump Case Gasket (369-65018-0)
- 1 × Pump Guide Plate Gasket (369-65029-0)
- 1 × Oil Seal (369-60223-0)
- 1 × Lower Pump Case Gasket (369-65020-0)
- 1 × O-Ring (369-66021-1)
- 1 × O-Ring (332-66032-0)
Installation Notes
- Disconnect the spark plug wire and drain the gearcase oil into a suitable container.
- Remove the bolts securing the lower unit to the outboard midsection and carefully detach the lower unit.
- Disassemble the water-pump housing and impeller, noting the orientation of all parts.
- Remove the old seals, O-rings and gaskets from the gearcase and water-pump components without scratching sealing surfaces.
- Clean all mating surfaces thoroughly and remove old gasket material and corrosion.
- Install the replacement seals and gaskets from the kit. Lightly lubricate rubber O-rings and seal lips with suitable marine grease where appropriate.
- Reassemble the water pump and lower-unit components in the reverse order of disassembly.
- Reinstall the lower unit and tighten the fasteners to the engine manufacturer's specified torque.
- Refill the gearcase with the recommended lower-unit oil to the correct level.
Troubleshooting & FAQ
How do I know if my lower-unit seals are failing?
Common signs include milky or water-contaminated gear oil, visible oil leakage around the propeller shaft or driveshaft housing, or an unusual odor from the gear oil. Inspect the gear lubricant regularly, especially during scheduled service.
Will this kit fix a leak from my gearcase?
This kit replaces the listed common seals and gaskets for compatible applications. If a leak continues after installation, inspect the housing, shafts, bearings and sealing surfaces for cracks, wear or damage.
What is the difference between this kit and an OEM version?
This listing is for an aftermarket replacement kit rather than an OEM component. Compare the listed contents, dimensions and reference numbers with your original parts before installation.
Do I need special tools for installation?
Standard mechanic's tools are generally required. A seal puller can help remove old seals safely, and a torque wrench is recommended for correctly tightening lower-unit fasteners.
How often should lower-unit seals be replaced?
There is no universal replacement interval. Inspect the gearcase for water intrusion and oil leakage during regular maintenance, and replace seals when the lower unit is serviced or symptoms appear.
Is this an OEM part?
No. This is an aftermarket replacement kit intended for the listed applications and reference numbers.
How quickly is the order shipped?
Typical transit is 5–15 days, with standard shipping free to most regions. Expedited options may be available at checkout.
What are the warranty and return terms?
The product is covered by a 1-year warranty against manufacturing defects under normal use. Returns are accepted within the applicable standard return window when the item is unused and in its original condition.
Safety & Important Information
- Confirm the engine brand, model, year, stroke, horsepower and original part number before ordering.
- Compare the supplied parts with the originals before disassembly and installation.
- Do not install a part that differs in size, shape or sealing profile from the required application.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended when servicing the lower unit or water pump.
About Sea Sierra
- Pro-Grade Standards — We supply marine replacement parts intended for demanding real-world service conditions.
- Fast Global Fulfillment — Free standard delivery is available to most regions, with typical transit of 5–15 days.
- Manufacturer-Direct Value — Fair pricing with attention to materials and quality control.
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