140°F Thermostat Kit for OMC Cobra and Volvo Penta 7.4L & 8.2L – Replaces 3853983, 0769578, 0986506
140°F Thermostat Kit for OMC Cobra and Volvo Penta 7.4L & 8.2L – Replaces 3853983, 0769578, 0986506 is backordered and will ship as soon as it is back in stock.
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140°F Thermostat Kit for OMC Cobra and Volvo Penta 7.4L & 8.2L ...
140°F Thermostat Kit for OMC Cobra and Volvo Penta 7.4L & 8.2L – Replaces 3853983, 0769578, 0986506 is backordered and will ship as soon as it is back in stock.
Product Details
This 140°F (60°C) aftermarket thermostat kit is designed for specified OMC Cobra stern-drive and Volvo Penta stern-drive applications. The documented fitment is limited to 7.4L engines from 1994–1998 and 8.2L engines from 1998. Confirm the engine model, year, original thermostat temperature, and part numbers before ordering.
The kit replaces the thermostat reference 3853983 and is listed with OMC and Volvo Penta reference numbers 0769578 and 0986506. Sierra Marine 18-3676 is the corresponding 140°F thermostat kit reference.
- 140°F (60°C) thermostat opening temperature.
- Aftermarket replacement for the specified marine stern-drive cooling applications.
- Kit includes the thermostat, thermostat gasket, and O-ring.
- Component references are provided for identification and fitment verification.
Part Number Matrix
Use the references below to compare the replacement kit with the part installed on your engine. Part-number references do not replace verification of the complete model and year application.
| Reference type | Part number | Description |
|---|---|---|
| OMC / Volvo Penta reference | 3853983 | 140°F thermostat reference |
| OMC Cobra reference | 0769578 | Thermostat kit reference listed by the company catalog |
| OMC Cobra reference | 0986506 | Thermostat kit reference listed by the company catalog |
| Sierra Marine reference | 18-3676 | 140°F thermostat kit reference |
| Thermostat component | 3853983 | Thermostat included in the kit |
| Gasket component | 3852111 | Thermostat gasket included in the kit |
| O-ring component | 3852071 | O-ring included in the kit |
Engine Compatibility
The following applications are documented for this 140°F thermostat kit. Do not extend these applications to other engine sizes, years, or thermostat temperatures without confirming the applicable service information.
| Brand / drive type | Engine | Years | Stroke | Application notes |
|---|---|---|---|---|
| OMC Cobra stern drive | 7.4L V8 | 1994–1998 | 4-Stroke gasoline | 140°F thermostat kit application |
| Volvo Penta stern drive | 7.4 GL, 7.4 Gi, 7.4 GSi | Verify by engine model and year | 4-Stroke gasoline | Company-listed model family; confirm the original part before purchase |
| OMC Cobra / Volvo Penta stern drive | 8.2L V8 | 1998 | 4-Stroke gasoline | 140°F thermostat kit application |
| Volvo Penta stern drive | 8.2 GL, 8.2 GSi | Verify by engine model and year | 4-Stroke gasoline | Company-listed model family; confirm the original part before purchase |
Important: The available catalog evidence specifically identifies the 7.4L application as 1994–1998 and the 8.2L application as 1998. The kit should not be described as fitting all 4.3L, 5.0L, 5.7L, 5.8L, 8.1L, or 8.2L engines without an applicable model-specific confirmation.
Technical Specifications
- Product type
- Thermostat kit
- Thermostat temperature
- 140°F / 60°C opening temperature
- Application
- Marine gasoline stern-drive cooling systems
- Replacement type
- Aftermarket replacement
- Primary thermostat reference
- 3853983
- Documented engine range
- 7.4L, 1994–1998; 8.2L, 1998
What's in the Box
- 1 × 140°F (60°C) thermostat
- 1 × thermostat gasket, reference 3852111
- 1 × O-ring, reference 3852071
The included gasket and O-ring are kit components. Their availability as separate replacement parts does not change the package contents of this thermostat kit.
Installation Notes
- Allow the engine to cool completely and disconnect the battery before starting work.
- Close or isolate the applicable cooling-water and coolant sources according to the engine manufacturer's service procedure.
- Remove the thermostat housing cover and note the installed thermostat orientation.
- Remove the old thermostat, gasket, and O-ring. Clean the mating surfaces without damaging the housing.
- Install the new thermostat in the same orientation as the original component.
- Fit the supplied gasket and O-ring in the locations specified for your engine model.
- Reinstall the housing cover and tighten fasteners to the engine manufacturer's specified torque.
- Restore the cooling system, start the engine, and check for leaks and abnormal temperature behavior.
Installation procedures can vary between engine models. Use the applicable factory service information for torque values, coolant draining, refill, and bleeding procedures.
Troubleshooting & FAQ
What temperature does this thermostat open at?
This kit is listed as a 140°F (60°C) thermostat kit. Verify that your engine requires this temperature before installation.
Which engines are documented for this kit?
The company catalog documents 7.4L applications from 1994–1998 and 8.2L applications from 1998. It also lists Volvo Penta 7.4 GL, 7.4 Gi, 7.4 GSi, 8.2 GL, and 8.2 GSi model families. Confirm the exact engine model, year, and original part number.
What parts are included?
The kit includes one thermostat, one thermostat gasket, and one O-ring. The component references are thermostat 3853983, gasket 3852111, and O-ring 3852071.
Is this an OEM thermostat?
No. This listing is for an aftermarket replacement kit. The OEM and aftermarket reference numbers are supplied for identification and compatibility comparison only.
Can I use this kit on a 4.3L, 5.0L, 5.7L, or 5.8L engine?
Those applications are not confirmed for this specific kit by the company record used for this listing. Match your exact engine model, year, thermostat temperature, and original part number before ordering.
What are common signs of a thermostat problem?
Possible symptoms include overheating, an engine that runs unusually cool, unstable temperature readings, or coolant leakage near the thermostat housing. Diagnose the complete cooling system before replacing the thermostat.
Safety & Important Information
- Work only on a cool engine and follow the applicable marine engine service procedure.
- Do not rely on engine size alone for fitment; verify model, year, thermostat temperature, and original part number.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended when the cooling-system procedure or engine-specific requirements are uncertain.
About Sea Sierra
- Marine Parts Support — We provide replacement components for marine maintenance and repair applications.
- Fitment-Focused Listings — Product references and documented applications are presented to help customers verify compatibility.
- Practical Replacement Solutions — Aftermarket components are offered for routine marine service needs.
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