Lower Unit Seal Kit – Fits Tohatsu/Nissan 15HP, 20HP, 25HP and 30HP Outboards (Replaces 346650130, 332601030)
Lower Unit Seal Kit – Fits Tohatsu/Nissan 15HP, 20HP, 25HP and 30HP Outboards (Replaces 346650130, 332601030) is backordered and will ship as soon as it is back in stock.
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Lower Unit Seal Kit – Fits Tohatsu/Nissan 15HP, 20HP, 25HP and 30HP...
Lower Unit Seal Kit – Fits Tohatsu/Nissan 15HP, 20HP, 25HP and 30HP Outboards (Replaces 346650130, 332601030) is backordered and will ship as soon as it is back in stock.
Product Details
This Lower Unit Seal Kit is intended for servicing the lower gearcase on selected Tohatsu and Nissan outboard motors rated from 15HP through 30HP. The replacement seals and gaskets help restore proper sealing and reduce the risk of water intrusion and gear-oil leakage when installed correctly.
This aftermarket replacement is listed as a cross-reference for Tohatsu/Nissan part numbers 346650130 and 332601030. Always compare the part number, engine model and parts diagram before ordering.
- Installs in the lower gearcase unit.
- Includes seals and gaskets for lower-unit service.
- Designed as an aftermarket replacement for the listed applications and reference numbers.
Part Number Matrix
Use the following references to compare this replacement with your original part and service-manual information.
| Brand | Part Number |
|---|---|
| Tohatsu / Nissan | 346650130 |
| Tohatsu / Nissan | 332601030 |
Engine & Model Compatibility
The listed application range covers selected Tohatsu MFS and Nissan NSF four-stroke outboards from 15HP through 30HP. Model, production year, serial number and lower-unit configuration can affect fitment, so verify the complete engine identification before installation.
| Brand | Model | Rated HP | Stroke | Reference Part No. | Notes |
|---|---|---|---|---|---|
| Tohatsu | MFS15 | 15 | 4-Stroke | 346650130, 332601030 | Verify model and serial details. |
| Tohatsu | MFS20 | 20 | 4-Stroke | 346650130, 332601030 | Verify model and serial details. |
| Tohatsu | MFS25 | 25 | 4-Stroke | 346650130, 332601030 | Verify model and serial details. |
| Tohatsu | MFS30 | 30 | 4-Stroke | 346650130, 332601030 | Verify model and serial details. |
| Nissan | NSF15 | 15 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent; verify model and serial details. |
| Nissan | NSF20 | 20 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent; verify model and serial details. |
| Nissan | NSF25 | 25 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent; verify model and serial details. |
| Nissan | NSF30 | 30 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent; verify model and serial details. |
Technical Specs
- Product Type
- Lower Unit Seal Kit
- Application
- Selected Tohatsu and Nissan outboard lower gearcases
- Rated Engine Range
- 15HP–30HP
- Stroke
- 4-Stroke applications listed above
- Installation Location
- Lower gearcase unit
What’s in the Box
- Lower-unit service seals and gaskets included with the kit.
Individual seal and gasket quantities are not specified in the available product record. Compare the contents with the parts diagram and the components removed from your lower unit before beginning work.
Installation Notes
- Position the outboard vertically and place a drain pan beneath the lower unit.
- Remove the lower and upper gear-oil drain screws and allow the lubricant to drain completely.
- Unbolt and carefully slide the lower gearcase away from the outboard midsection.
- Remove the water-pump housing, impeller and bearing-carrier components as required to access the seals.
- Extract the old propeller-shaft and driveshaft seals carefully, noting their orientation and installation depth.
- Clean all sealing surfaces and remove old sealant, corrosion and debris.
- Lubricate the replacement seals with suitable marine grease and install them with the correct seal driver.
- Reassemble the lower unit in the reverse order, following the service manual for alignment, torque and sealant requirements.
- Refill the gearcase with the specified marine gear lubricant until lubricant flows from the upper vent opening, then reinstall both screws.
- Pressure- and vacuum-test the gearcase before returning the outboard to service.
Troubleshooting & FAQ
How can I confirm this kit fits my specific engine?
Cross-reference 346650130 or 332601030 with your engine’s service manual or parts diagram, then confirm the exact model, year and serial-number range. The engine must also have the corresponding lower-unit configuration.
What are the signs that lower-unit seals are failing?
Common signs include milky or creamy gear oil, visible oil around the propeller shaft or driveshaft, or repeated loss of gear lubricant. A pressure and vacuum test is the definitive diagnostic method.
How often should lower-unit seals be replaced?
There is no universal replacement interval. Inspect the seals during routine water-pump or lower-unit service and replace them whenever the gearcase is opened or a leak is found, following the engine manufacturer’s maintenance schedule.
Is installation suitable for a DIY mechanic?
Lower-unit seal replacement requires intermediate mechanical skill and tools such as a seal puller and seal driver. Professional installation is recommended if you are not comfortable disassembling and pressure-testing the gearcase.
How should the gearcase be tested after installation?
Use a suitable gearcase pressure tester and vacuum tester, and follow the manufacturer’s specified test values. Do not exceed the service-manual pressure limit. Check for leakage before operating the outboard.
Is additional sealant required?
Some lower-unit components may require marine-grade gasket compound or thread sealant, while others use only an O-ring or mechanical seal. Use sealant only where specified by the service manual.
Is this an OEM component?
No. This is an aftermarket replacement product. The listed Tohatsu/Nissan numbers are reference numbers for comparison and fitment verification.
What should I verify before ordering?
Compare the original part, reference numbers, engine model, horsepower, stroke, year and serial number. Do not rely on horsepower alone because lower-unit configurations may vary.
Safety & Important Information
- Verify the part numbers, engine identification and lower-unit configuration before purchase.
- Do not operate the outboard if gear oil is contaminated or the gearcase fails a pressure or vacuum test.
- Follow the engine manufacturer’s service manual for disassembly, torque values, lubricant type and sealant requirements.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended when special tools or gearcase disassembly are required.
About Sea Sierra
- Marine replacement parts selected for practical service and repair applications.
- Product information is organized to help you compare reference numbers and engine fitment details.
- For best results, verify every application detail against the manufacturer’s parts diagram before ordering.
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