180°F (82°C) Thermostat for Volvo Penta Sterndrive Engines – Replaces 875580, Sierra 18-3666
180°F (82°C) Thermostat for Volvo Penta Sterndrive Engines – Replaces 875580, Sierra 18-3666 is backordered and will ship as soon as it is back in stock.
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180°F (82°C) Thermostat for Volvo Penta Sterndrive Engines – Replac...
180°F (82°C) Thermostat for Volvo Penta Sterndrive Engines – Replaces 875580, Sierra 18-3666 is backordered and will ship as soon as it is back in stock.
Product Details
This 180°F (82°C) marine engine thermostat is designed for selected Volvo Penta stern-drive and out-drive applications. It helps regulate engine operating temperature and is listed for the Volvo Penta AQ120, AQ125, AQ131, AQ140, AQ145, AQ151, AQ171, B21, B23, B230, 250, and 251 engine families.
The thermostat is an aftermarket replacement for Volvo Penta OEM part number 875580 and is cross-referenced with Sierra part number 18-3666. Verify the engine model and the number on your original thermostat before ordering.
- 180°F (82°C) temperature rating.
- For selected Volvo Penta stern-drive and out-drive cooling systems.
- Replacement thermostat for the listed OEM and aftermarket references.
- Single thermostat supplied; gasket or seal ring is not confirmed as included.
Part Number Matrix
Use these references to compare the replacement thermostat with your existing part.
| Brand | Part Number | Reference Type |
|---|---|---|
| Volvo Penta | 875580 | OEM reference |
| Sierra | 18-3666 | Aftermarket reference |
Engine & Model Compatibility
This listing covers the following Volvo Penta engine families. Model, year, serial-number, cooling-system, and installation conditions can vary within an engine family, so confirm the original thermostat and application before installation.
| Brand | Engine Model or Family | Stroke | Temperature Rating | OEM Reference |
|---|---|---|---|---|
| Volvo Penta | AQ120 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | AQ125 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | AQ131 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | AQ140 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | AQ145 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | AQ151 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | AQ171 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | B21, B23, B230 | Verify for your engine | 180°F (82°C) | 875580 |
| Volvo Penta | 250, 251 | Verify for your engine | 180°F (82°C) | 875580 |
Technical Specs
- Product Type
- Marine engine thermostat
- Application
- Selected Volvo Penta stern-drive and out-drive cooling systems
- Temperature Rating
- 180°F (82°C)
- OEM Reference
- Volvo Penta 875580
- Aftermarket Reference
- Sierra 18-3666
- Product Configuration
- Single thermostat
- Seal or Gasket
- Not confirmed as included; reuse only if serviceable or obtain the required seal separately
What’s in the Box
- 1 x 180°F (82°C) thermostat
Important: This listing is for the thermostat only. A seal ring or gasket is not confirmed as part of the package.
Installation Notes
- Allow the engine to cool completely before beginning service.
- Follow the engine manufacturer’s procedures for relieving pressure and draining or containing coolant as required.
- Locate the thermostat housing and remove the cover according to the service instructions for your engine.
- Remove the old thermostat and note its orientation before taking it out.
- Clean the housing and mating surfaces carefully. Do not damage the sealing surfaces.
- Install the replacement thermostat in the same orientation as the original part.
- Install a suitable new gasket or seal if the original seal is damaged or the service procedure requires replacement. No gasket or seal is confirmed to be included with this product.
- Reinstall the thermostat housing and tighten the fasteners to the engine manufacturer’s specified torque.
- Restore the cooling system as required, then start the engine and check for leaks and correct temperature operation.
Troubleshooting & FAQ
What temperature is this thermostat rated for?
This thermostat is rated for 180°F (82°C).
Is this a complete thermostat kit?
This item is a single thermostat rather than a bundled kit. A gasket or seal ring is not confirmed as included, so check the existing seal and obtain a replacement separately if required.
Which part numbers does this thermostat replace?
It is listed as a replacement for Volvo Penta OEM reference 875580 and is cross-referenced with Sierra 18-3666.
Which Volvo Penta engines are listed for this thermostat?
The listed engine families are AQ120, AQ125, AQ131, AQ140, AQ145, AQ151, AQ171, B21, B23, B230, 250, and 251. Confirm the exact engine application, serial information, cooling arrangement, and original part number before ordering.
Is this an OEM thermostat?
This listing is for an aftermarket replacement, not a Volvo Penta-branded OEM component.
Safety & Important Information
- Verify the engine model, cooling-system configuration, original thermostat, and reference number before purchase.
- Do not rely on horsepower or model-family information alone when confirming fitment.
- Allow the engine to cool before opening the thermostat housing or cooling system.
- Use the correct gasket or seal for your application; this product is supplied as a thermostat only.
- Professional installation is recommended when the correct service procedure or torque specification is not available.
About Sea Sierra
- Marine Parts Focus — We supply replacement components for marine engine maintenance and repair.
- Application Guidance — Compare the listed references and engine information with your original part before ordering.
- Customer Support — Contact support if you need help comparing an existing part number or application detail.
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