Thermostat Kit – Fits Tohatsu/Nissan 2-50 HP Outboards (Replaces 346-01030, 345-01030)
Thermostat Kit – Fits Tohatsu/Nissan 2-50 HP Outboards (Replaces 346-01030, 345-01030) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Thermostat Kit – Fits Tohatsu/Nissan 2-50 HP Outboards (Replaces 34...
Thermostat Kit – Fits Tohatsu/Nissan 2-50 HP Outboards (Replaces 346-01030, 345-01030) is backordered and will ship as soon as it is back in stock.
Product Details
This Thermostat Kit – Fits Tohatsu/Nissan 2-50 HP Outboards (Replaces 346-01030, 345-01030) is designed for a wide range of Tohatsu and Nissan 2-stroke and 4-stroke models. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.
This kit serves as a direct replacement for Tohatsu/Nissan part numbers 346-01030-0, 346-01030-1, 345-01030-0, 345-01030-1, 350-01030-1, and 3H6-01030-0.
- Maintains proper engine operating temperature at 50°C (122°F).
- Engineered as a direct replacement for a hassle-free installation.
- Includes thermostat, housing gasket, and seals for a complete service.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Tohatsu / Nissan | 346-01030-0 |
| Tohatsu / Nissan | 346-01030-1 |
| Tohatsu / Nissan | 345-01030-0 |
| Tohatsu / Nissan | 345-01030-1 |
| Tohatsu / Nissan | 350-01030-1 |
| Tohatsu / Nissan | 3H6-01030-0 |
| Tohatsu / Nissan | 346-01030 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Tohatsu / Nissan Compatibility: This thermostat fits a wide variety of 2-stroke and 4-stroke models from 2 HP to 50 HP. Please verify your specific model is listed.
| Brand | Model | Rated HP | Stroke | OEM Part No. |
|---|---|---|---|---|
| Tohatsu | MFS2 | 2 | 4-Stroke | 346-01030 |
| Tohatsu | MFS2.5 | 2.5 | 4-Stroke | 346-01030 |
| Tohatsu | MFS3.5C | 3.5 | 4-Stroke | 346-01030 |
| Tohatsu | MFS5 | 5 | 4-Stroke | 346-01030 |
| Tohatsu | MF6 | 6 | 4-Stroke | 346-01030 |
| Tohatsu | M8B | 8 | 2-Stroke | 346-01030 |
| Tohatsu | M9.8B | 9.8 | 2-Stroke | 346-01030 |
| Tohatsu | M9.9D2 | 9.9 | 2-Stroke | 346-01030 |
| Tohatsu | M15D2 | 15 | 2-Stroke | 346-01030 |
| Tohatsu | M18E2 | 18 | 2-Stroke | 346-01030 |
| Tohatsu | M25C3 | 25 | 2-Stroke | 346-01030 |
| Tohatsu | M30A4 | 30 | 2-Stroke | 346-01030 |
| Tohatsu | MD40B, MD40B2, M40C | 40 | 2-Stroke | 346-01030 |
| Tohatsu | MD50B, MD50B2 | 50 | 2-Stroke | 346-01030 |
| Nissan | NS3.5B2 | 3.5 | 2-Stroke | 346-01030 |
| Nissan | NS5B2 | 5 | 2-Stroke | 346-01030 |
| Nissan | NS6B2 | 6 | 2-Stroke | 346-01030 |
| Nissan | NS25D2 | 25 | 2-Stroke | 346-01030 |
| Nissan | NS30D2 | 30 | 2-Stroke | 346-01030 |
| Nissan | NS40D2 | 40 | 2-Stroke | 346-01030 |
Technical Specs
- Product Type
- Thermostat Kit
- Operating Temperature
- 50°C (122°F)
- Installation
- Direct replacement
- Housing Material
- Stainless steel housing with corrosion-resistant spring
- Included Components
- Includes housing gasket and thermostat seals
What’s in the Box
- 1x Thermostat (Replaces 346-01030)
- 1x Thermostat Housing Gasket
- 2x Thermostat Seals
Installation Notes
- Ensure the engine is completely cool and disconnect the negative battery terminal for safety.
- Locate the thermostat housing on the engine block. Place a drain pan underneath to catch any spilling coolant.
- Carefully remove the bolts securing the housing cover. Note the orientation of the old thermostat before removing it and its gasket.
- Thoroughly clean the mating surfaces of the housing and cover, ensuring no old gasket material remains.
- Install the new thermostat in the correct orientation, followed by the new gasket and seals provided in the kit.
- Reinstall the housing cover, tightening the bolts evenly to the manufacturer's recommended torque specification to prevent leaks.
- Reconnect the battery, refill the cooling system with the appropriate coolant, and run the engine to check for leaks and proper temperature circulation.
Troubleshooting & FAQ
What are the signs of a failed thermostat?
Common symptoms include the engine overheating at normal speeds, or conversely, failing to reach its proper operating temperature (running too cold). An erratic temperature gauge reading can also indicate a problem.
Is this thermostat set to the factory temperature?
Yes, this thermostat is calibrated to the standard 50°C (122°F) operating temperature specified for these engines, ensuring proper performance and fuel efficiency.
How can I confirm this kit fits my specific engine?
Cross-reference your original part number with our Part Number Matrix. Then, verify your engine’s model, horsepower, and stroke are listed in the Engine & Model Compatibility table. Do not rely on one data point alone.
Is there a recommended replacement interval?
Thermostats don't have a fixed replacement schedule, but it's good practice to inspect them during regular cooling system service (e.g., every 2-3 years) or replace them if you're replacing the water pump.
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 part 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.
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