76°C (169°F) Thermostat Kit – Fits Volvo Penta 30 & 40 Series Diesel Engines (Replaces 3831425, 875787)
76°C (169°F) Thermostat Kit – Fits Volvo Penta 30 & 40 Series Diesel Engines (Replaces 3831425, 875787) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
76°C (169°F) Thermostat Kit – Fits Volvo Penta 30 & 40 Series D...
Product Details
This 76°C (169°F) Thermostat Kit is engineered for Volvo Penta 30 and 40 series marine diesel engines, including AD, AQAD, MD, TAMD, and TMD models. It ensures your engine operates within the optimal temperature range for performance and longevity.
It serves as a direct replacement for Volvo Penta part numbers 3831425, 875787, 824200, and 1544297, as well as Sierra 18-3660.
- Installation Method: Direct OEM-style fit
- Operating Temperature: Opens at 76°C (169°F)
- Engine Quantity: Note that some engines require one thermostat while others require two.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Volvo Penta | 3831425 |
| Volvo Penta | 875787 |
| Volvo Penta | 824200 |
| Volvo Penta | 1544297 |
| Sierra | 18-3660 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Volvo Penta Diesel Engines: This part fits a wide range of 30 and 40 series models. Please check the 'Notes' column for the quantity required for your specific engine.
| Brand | Model | Stroke | OEM Part No. | Notes |
|---|---|---|---|---|
| Volvo Penta | AD30A | 4-Stroke | 3831425, 875787 | 2 required per engine |
| Volvo Penta | AQAD30A | 4-Stroke | 3831425, 875787 | 2 required per engine |
| Volvo Penta | MD30A | 4-Stroke | 3831425, 875787 | 2 required per engine |
| Volvo Penta | TAMD30A | 4-Stroke | 3831425, 875787 | 2 required per engine |
| Volvo Penta | TMD30A | 4-Stroke | 3831425, 875787 | 2 required per engine |
| Volvo Penta | AD40B | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | AQAD40A | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | AQAD40B | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | AQD40A | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | MD40A | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | TAMD40A | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | TAMD40B | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | TMD40A | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | TMD40B | 4-Stroke | 3831425, 875787 | 1 required per engine |
| Volvo Penta | TMD40C | 4-Stroke | 3831425, 875787 | 1 required per engine |
Technical Specs
- Product Type
- Marine Engine Thermostat Kit
- Installation
- Direct OEM Replacement
- Opening Temperature
- 76°C (169°F)
- Fuel Type
- Diesel
- Connection
- Direct Fit
- Dimensions
- 15.0cm L x 10.0cm W x 5.5cm H
- Fitting Type
- Direct Fit
- Operating Temperature
- 76°C (169°F) opening temperature
- Other Technical Attributes
- Required Quantity: 1 per engine (AD40B, AQAD40A, AQAD40B, AQD40A, MD40A, TAMD40A, TAMD40B, TMD40A, TMD40B, TMD40C); 2 per engine (AD30A, AQAD30A, MD30A, TAMD30A, TMD30A)
What’s in the Box
- 1 x Thermostat
- 1 x Gasket
Installation Notes
- Ensure the engine is completely cool and disconnect the battery.
- Drain the engine coolant into a suitable container.
- Locate the thermostat housing on the engine.
- Remove the bolts securing the housing cover. Note the orientation of the housing.
- Carefully remove the old thermostat and gasket.
- Clean both the housing and cover mating surfaces thoroughly, removing all old gasket material.
- Install the new thermostat in the correct orientation, followed by the new gasket.
- Re-secure the housing cover and torque bolts to manufacturer specifications.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and carefully check for any leaks around the housing as the engine warms up.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Common signs of a faulty thermostat include engine overheating, running too cool (not reaching operating temperature), erratic temperature gauge readings, or visible coolant leaks from the thermostat housing.
How many thermostats do I need for my engine?
Volvo Penta 30-series engines (AD30A, AQAD30A, etc.) require two thermostats. The 40-series engines (AD40B, AQAD40B, etc.) require one thermostat. Please verify with our compatibility list.
Why is the correct opening temperature important?
The 76°C (169°F) opening temperature is critical for diesel engines to reach optimal combustion temperature quickly, ensuring fuel efficiency, reducing engine wear, and minimizing emissions.
Is a gasket included with this kit?
Yes, this kit includes the necessary gasket for a complete installation, ensuring a proper seal.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility and batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit is 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 and specifications against 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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