Thermostat Kit – Fits Volvo Penta 4.3L, 5.0L, 5.7L, 7.4L, 8.1L (Replaces 0769578, 3853983, 3852111)
Thermostat Kit – Fits Volvo Penta 4.3L, 5.0L, 5.7L, 7.4L, 8.1L (Replaces 0769578, 3853983, 3852111) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat Kit – Fits Volvo Penta 4.3L, 5.0L, 5.7L, 7.4L, 8.1L (Rep...
Product Details
This Thermostat Kit – Fits Volvo Penta 4.3L, 5.0L, 5.7L, 7.4L, 8.1L is designed for a broad range of Volvo Penta gasoline marine engines, including the 4.3L, 5.0L, and 5.7L V6/V8 series (1994–present) and the 7.4L, 8.1L, and 8.2L V8 Big Block series (1993–present). It is also compatible with OMC Cobra 4.3L to 5.8L models from 1994 to 1998 and select earlier engines.
It serves as a direct replacement for Volvo Penta part numbers 0769578, 3853983, and 3852111; OMC 0986506 and 3853983; and Sierra 18-3676.
- Installs as a direct OEM-equivalent replacement.
- Engineered for closed cooling systems.
- Includes thermostat, gasket, and O-ring for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Volvo Penta | 0769578 |
| Volvo Penta | 3853983 |
| Volvo Penta | 3852111 |
| OMC | 0986506 |
| OMC | 3853983 |
| Sierra | 18-3676 |
| WgxzXyl | WgxzXyl123 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Volvo Penta engines, this kit fits various V6 and V8 models from 1993 to present. Please verify your specific model and year range in the compatibility chart.
For OMC engines, this kit is primarily for Cobra stern drive models manufactured between 1994 and 1998, as well as select earlier high-horsepower models.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Volvo Penta | 7.4-BY, 7.4-EF, 7.4-LK, 7.4-WT | 7.4L | 4-Stroke | 1993–2000 | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 7.4Gi-BY, 7.4Gi-EF, 7.4Gi-HU, 7.4Gi-LK, 7.4Gi-NC, 7.4Gi-WT, 7.4GiPEFS | 7.4L | 4-Stroke | 1993–2000 | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 7.4GL-BY, 7.4GL-HU, 7.4GL-LK, 7.4GL-MD, 7.4GL-NC | 7.4L | 4-Stroke | 1993–2000 | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 7.4GSi-BY, 7.4GSi-EF, 7.4GSi-HU, 7.4GSi-LK, 7.4GSi-NC, 7.4GSi-WT, 7.4GSiPEFS | 7.4L | 4-Stroke | 1993–2000 | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.1Gi-A to 8.1Gi-J | 8.1L | 4-Stroke | 2000–Present | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.1GiC-400-J/Q, 8.1GiCE-400-J/M/P/Q | 8.1L | 4-Stroke | 2000–Present | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.1GiE-J/K/M/P, 8.1Gii-A to H | 8.1L | 4-Stroke | 2000–Present | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.1GSi-A, 8.1GSii-A | 8.1L | 4-Stroke | 2000–Present | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.1GXi-A to J, 8.1GXiE-J/K/M/P | 8.1L | 4-Stroke | 2000–Present | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.1GXii-A to G | 8.1L | 4-Stroke | 2000–Present | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.1OSi-A to D/J, 8.1OSiE-J | 8.1L | 4-Stroke | 2000–Present | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | 8.2Gi-EF/WT, 8.2GL-HU/MD, 8.2GSi-BY/EF/LK/NC/WT | 8.2L | 4-Stroke | 1993–2000 | 0769578/3853983 | Big Block V8 Series |
| Volvo Penta | DPX375-A/B/BF, DPX385/XEFS, DPX415/XEFS, DPX420-A/B/F | N/A | 4-Stroke | 1994–2000 | 0769578/3853983 | Drive Models |
| Volvo Penta | 4.3L (All Models) | 4.3L | 4-Stroke | 1994–Present | 0769578/3853983 | V6 Series |
| Volvo Penta | 5.0L (All Models) | 5.0L | 4-Stroke | 1994–Present | 0769578/3853983 | V8 Series |
| Volvo Penta | 5.7L (All Models Except OSi) | 5.7L | 4-Stroke | 1994–Present | 0769578/3853983 | V8 Series |
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| OMC | Cobra 4.3L | 4.3L | 4-Stroke | 1994–1998 | 0986506/3853983 | Stern Drive |
| OMC | Cobra 5.0L | 5.0L | 4-Stroke | 1994–1998 | 0986506/3853983 | Stern Drive |
| OMC | Cobra 5.7L | 5.7L | 4-Stroke | 1994–1998 | 0986506/3853983 | Stern Drive |
| OMC | Cobra 5.8L | 5.8L | 4-Stroke | 1994–1998 | 0986506/3853983 | Stern Drive |
| OMC | Cobra | 80-200 HP | 4-Stroke | 1968–1969 | 0986506/3853983 | Stern Drive |
Technical Specs
- Product Type
- Thermostat Kit
- Installation
- Direct OEM replacement
- Fuel Type
- Gasoline
- Dimensions
- 17.0" L x 11.0" W x 3.0" H
- Weight
- 870g (1.92 lb)
- Operating Temperature
- 60°C (140°F) opening temperature
- Other Technical Attributes
- Closed cooling system compatibility
- Warranty
- 1-year (JLM Marine)
What’s in the Box
- 1 x Thermostat (3853983)
- 1 x Gasket (3852111)
- 1 x O-ring (3852071)
Installation Notes
- Ensure the engine is cool and disconnect the battery.
- Drain the engine coolant into a suitable container.
- Locate the thermostat housing on the engine and remove the bolts securing it.
- Carefully lift the housing to access the old thermostat. Note its orientation before removing.
- Remove the old thermostat, gasket, and O-ring. Thoroughly clean any corrosion or old gasket material from the housing and engine mating surfaces.
- Place the new thermostat into the engine, ensuring it is seated in the correct orientation.
- Install the new gasket and O-ring on the housing as required.
- Re-secure the thermostat housing and tighten the bolts to the manufacturer's recommended torque specification.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and check for any leaks around the housing as the engine warms up.
Troubleshooting & FAQ
How do I confirm this kit fits my specific engine?
The surest way is to match your engine's model, year, and (if possible) the part number on your existing thermostat to the information in our compatibility tables. Pay close attention to notes, such as engine series or specific sub-models.
What are the common signs of a failing thermostat?
Symptoms of a bad thermostat include engine overheating (if stuck closed) or the engine taking too long to reach operating temperature (if stuck open). You might also notice erratic temperature gauge readings or coolant leaks around the thermostat housing.
At what temperature does this thermostat begin to open?
This thermostat is rated to begin opening at 60°C (140°F), helping the engine reach its optimal operating temperature efficiently.
Is the O-ring necessary for all installations?
Yes. Both the gasket and the O-ring are critical for creating a leak-proof seal. Different engine models may use one or both. Always replace all included seals to prevent coolant leaks.
How often should a marine thermostat be replaced?
While there is no fixed interval, it is good practice to inspect the thermostat during routine cooling system service (every 2-3 years) and replace it if there are signs of corrosion, sticking, or if the engine is not maintaining the correct temperature.
Can I use this kit in a raw water (saltwater) cooling system?
This kit is primarily designed for closed (freshwater) cooling systems. While the materials are corrosion-resistant, life expectancy may be reduced in a raw-water-cooled engine. Ensure compatibility with your specific cooling system type.
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.
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