Lower Unit Seal Kit – Fits Tohatsu/Nissan 15-30HP Outboards (Replaces 346650130, 332601030)
Lower Unit Seal Kit – Fits Tohatsu/Nissan 15-30HP Outboards (Replaces 346650130, 332601030) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Lower Unit Seal Kit – Fits Tohatsu/Nissan 15-30HP Outboards (Replac...
Product Details
This Lower Unit Seal Kit provides all the necessary components to service the lower gearcase on Tohatsu and Nissan 4-stroke outboard motors in the 15HP to 30HP range. It's engineered to restore factory sealing performance and prevent water intrusion and oil leaks.
This kit serves as a direct replacement for Tohatsu/Nissan OEM part numbers 346650130 and 332601030.
- Installs in the lower gearcase unit.
- Includes all required seals and gaskets for a complete overhaul.
- Designed to meet or exceed original equipment specifications for fit and function.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Tohatsu / Nissan | 346650130 |
| Tohatsu / Nissan | 332601030 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Tohatsu outboards, this kit fits MFS series 4-stroke models from 15HP to 30HP.
For Nissan outboards, this kit is compatible with the equivalent NSF series 4-stroke models from 15HP to 30HP.
| Brand | Model | Rated HP | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|---|
| Tohatsu | MFS15 | 15 | 4-Stroke | 346650130, 332601030 | |
| Tohatsu | MFS20 | 20 | 4-Stroke | 346650130, 332601030 | |
| Tohatsu | MFS25 | 25 | 4-Stroke | 346650130, 332601030 | |
| Tohatsu | MFS30 | 30 | 4-Stroke | 346650130, 332601030 | |
| Nissan | NSF15 | 15 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent |
| Nissan | NSF20 | 20 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent |
| Nissan | NSF25 | 25 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent |
| Nissan | NSF30 | 30 | 4-Stroke | 346650130, 332601030 | Nissan-branded equivalent |
Technical Specs
- Product Type
- Lower Unit Seal Kit
- Installation
- Lower Gearcase Unit
What’s in the Box
- All seals and gaskets required for lower unit service.
Installation Notes
- Position the outboard vertically and place a drain pan under the lower unit.
- Remove the lower and upper gear oil drain screws and allow the oil to drain completely.
- Unbolt and carefully slide the lower gearcase unit away from the outboard's midsection.
- Systematically remove the water pump housing, impeller, and bearing carrier to access the old seals.
- Carefully extract the old propeller shaft and driveshaft seals, noting their orientation.
- Clean all sealing surfaces thoroughly, ensuring they are free of old sealant, corrosion, and debris.
- Lubricate the new seals with marine grease and install them using an appropriate seal driver.
- Reassemble all components in reverse order, ensuring correct alignment and torque specifications.
- Refill the gearcase with fresh marine gear lubricant until it flows from the upper vent hole, then reinstall both screws.
Troubleshooting & FAQ
How can I confirm this kit fits my specific engine model?
Your best confirmation method is to cross-reference the OEM part numbers (346650130, 332601030) with your engine's service manual or parts diagram. While the table lists compatible models, an OEM number match is the most reliable check.
What are the signs that my lower unit seals are failing?
Common signs include milky or creamy-looking gear oil (indicating water intrusion), visible oil leaks around the propeller shaft or driveshaft, or a recurring loss of gear lubricant. A pressure and vacuum test of the gearcase is the definitive diagnostic method.
How often should I replace my lower unit seals?
There is no fixed interval, but seals should be inspected during every water pump service (typically every 1-2 years or 100-200 hours). It is standard practice to replace them whenever the gearcase is opened for service to ensure reliability.
Is this a difficult installation for a DIY mechanic?
Replacing lower unit seals requires intermediate mechanical skill and some special tools, such as a seal puller and driver. If you are not comfortable disassembling the gearcase, we strongly recommend professional installation to prevent damage.
How can I test the gearcase for leaks after installation?
A leak test requires a gearcase pressure tester. The standard procedure is to pressurize the unit to approximately 10-12 PSI and check that it holds pressure for several minutes. Then, apply a vacuum of 5-7 in-Hg and ensure it holds. Never exceed the manufacturer's specified pressure.
Do I need any special sealant in addition to this kit?
While the kit contains the primary seals, you may need a suitable marine-grade gasket sealing compound for surfaces like the bearing carrier O-ring or where specified by your service manual to ensure a perfect seal.
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
- 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 QC.
Payment & Security
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