Thermostat Kit, 122°F (50°C) – Fits Selected Tohatsu and Nissan 2–50 HP Outboards
Thermostat Kit, 122°F (50°C) – Fits Selected Tohatsu and Nissan 2–50 HP Outboards 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, 122°F (50°C) – Fits Selected Tohatsu and Nissan 2–5...
Thermostat Kit, 122°F (50°C) – Fits Selected Tohatsu and Nissan 2–50 HP Outboards is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket thermostat kit is designed for selected Tohatsu and Nissan outboard engines using a 122°F (50°C) thermostat. The listed applications cover selected 2–50 HP models, including M, MD, MF, MFS, NS, and NSD series engines. Because application can vary by model, year, serial range, and cooling-system configuration, confirm the engine model and the original thermostat part number before ordering.
The kit is listed as a replacement for Tohatsu references 345-01030-0, 345010300M, 345010301M, 346-01030-0, 346-01030-1, 350-01030-1, and 3H6-01030-0. These numbers are manufacturer or interchange references, not the seller's internal product identifier.
- Replacement thermostat service kit for selected Tohatsu and Nissan outboards.
- 122°F (50°C) thermostat opening-temperature rating.
- Includes the thermostat, housing gasket, and two thermostat seals as listed.
- Verify the original part number and complete engine identification before installation.
Part Number Matrix
Use the following references to compare the thermostat with the part removed from your engine.
| Brand | Part Number |
|---|---|
| Tohatsu | 345-01030-0 |
| Tohatsu | 345010300M |
| Tohatsu | 345010301M |
| Tohatsu | 346-01030-0 |
| Tohatsu | 346-01030-1 |
| Tohatsu | 350-01030-1 |
| Tohatsu | 3H6-01030-0 |
Engine & Model Compatibility
The applications below are the listed model references for this thermostat kit. Model names alone may not identify every production variant; check the model code, year or serial range where applicable, stroke type, and OEM part number together.
| Brand | Model | Rated HP | Stroke / Configuration | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Tohatsu | MFS2 | 2 | 4-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | MFS2.5 | 2.5 | 4-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | MFS3.5C | 3.5 | 4-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | MFS5 | 5 | 4-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | MF6 | 6 | 4-Stroke | 2006 | 345-01030-0 | Year-specific application as listed. |
| Tohatsu | M8B | 8 | 2-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | M9.8B | 9.8 | 2-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | M9.9D2 | 9.9 | 2-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | M15D2 | 15 | 2-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | M18E2 | 18 | 2-Stroke | Not specified | 345-01030-0 | Confirm the original part number. |
| Tohatsu | M25C3 | 25 | 2-Stroke | 2003 | 345-01030-0 | Year-specific application as listed. |
| Tohatsu | M30A4 | 30 | 2-Stroke | 2003 | 345-01030-0 | Year-specific application as listed. |
| Tohatsu | M40C | 40 | 2-Stroke | 2004 | 345-01030-0 | Year-specific application as listed. |
| Tohatsu | MD40A, MD40B, MD40B2 | 40 | TLDI direct-injection 2-Stroke | 2010–2014 | 345010300M | Verify model and serial range. |
| Tohatsu | MD50A, MD50B, MD50B2 | 50 | TLDI direct-injection 2-Stroke | 2010–2014 | 345010300M | Verify model and serial range. |
| Nissan | NS25C3 | 25 | 2-Stroke | 2003 | 345-01030-0 | Year-specific application as listed. |
| Nissan | NS30A4 | 30 | 2-Stroke | 2003 | 345-01030-0 | Year-specific application as listed. |
| Nissan | NS40C | 40 | 2-Stroke | 2004 | 345-01030-0 | Year-specific application as listed. |
| Nissan | NSD40B, NSD40B2 | 40 | TLDI direct-injection 2-Stroke | 2010–2014 | 345010300M | Verify model and serial range. |
| Nissan | NSD50B, NSD50B2 | 50 | TLDI direct-injection 2-Stroke | 2010–2014 | 345010300M | Verify model and serial range. |
Technical Specifications
- Product Type
- Thermostat kit with housing gasket and seals
- Temperature Rating
- 122°F (50°C) opening temperature
- Installation
- Replacement installation in the existing thermostat housing
- Housing Finish
- Silver/metallic as listed
What's in the Box
- 1 × Thermostat
- 1 × Thermostat housing gasket
- 2 × Thermostat seals
Installation Notes
- Allow the engine to cool completely and follow the service manual's safety procedures.
- Disconnect the battery if required by the engine manufacturer's service procedure.
- Locate the thermostat housing and remove the cover fasteners.
- Remove the old thermostat, gasket, and seals, noting their orientation.
- Clean the mating surfaces carefully without damaging the housing or cover.
- Install the replacement thermostat, seals, and gasket in the correct orientation.
- Reinstall the housing cover and tighten the fasteners to the manufacturer's specified torque.
- Restore the cooling system as required for the engine, start it, and check for leaks and proper temperature control.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Possible symptoms include overheating, running below the expected operating temperature, inconsistent temperature behavior, or restricted cooling-system flow. Diagnose the cause before replacing the thermostat.
What does the 122°F (50°C) rating mean?
It identifies the thermostat's listed opening temperature. The thermostat begins opening near this temperature to regulate cooling-water flow through the engine according to the engine's design.
Is this a complete kit?
The listed package contains one thermostat, one thermostat housing gasket, and two thermostat seals. Confirm that these components match the arrangement on your engine before installation.
Will this fit a model year not shown?
Do not rely on horsepower alone. Compare the exact model, year or serial range, stroke/configuration, and original OEM part number with the information above and the engine service documentation.
When should a thermostat be replaced?
Replace it when testing identifies a fault, when it is damaged or contaminated, or during cooling-system service if the manufacturer's maintenance procedure calls for replacement. Follow the engine service manual for testing and maintenance intervals.
Is this an OEM part?
No. This listing is for an aftermarket replacement kit. The OEM numbers shown are reference numbers used for application comparison.
What are the shipping speed and cost?
Available shipping methods, delivery estimates, and shipping charges are shown at checkout and vary by destination and service level.
What is the warranty and return policy?
Warranty and return terms are governed by the seller's current policies. Review the applicable policy before purchase and contact support if the delivered item does not match the listing or arrives damaged.
Safety & Important Information
- Verify the complete engine model, year or serial range, stroke/configuration, and original part number before ordering.
- Compare the supplied parts with the removed components before installation.
- Use the manufacturer's service manual for torque values, cooling-system procedures, testing, and safety requirements.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended when the correct procedure or engine application is uncertain.
About Sea Sierra
- Pro-Grade Standards — Marine replacement parts selected for fit, function, and service use.
- Global Fulfillment — Shipping options and delivery estimates are provided at checkout.
- Manufacturer-Direct Value — Competitive replacement-part pricing with application information to support part selection.
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