160°F Thermostat Kit for OMC Cobra V6/V8 Marine Engines – Replaces 3856961
160°F Thermostat Kit for OMC Cobra V6/V8 Marine Engines – Replaces 3856961 is backordered and will ship as soon as it is back in stock.
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160°F Thermostat Kit for OMC Cobra V6/V8 Marine Engines – Replaces ...
160°F Thermostat Kit for OMC Cobra V6/V8 Marine Engines – Replaces 3856961 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket 160°F (71°C) thermostat kit is designed for specified OMC Cobra stern-drive and inboard marine gasoline engines. It replaces the OMC thermostat reference 3856961 and is intended for the OMC applications listed below.
The kit includes the thermostat, thermostat gasket, and O-ring for a complete thermostat service. Confirm the exact engine model, year, cooling configuration, and existing part dimensions before ordering.
- 160°F (71°C) thermostat opening temperature.
- Designed for specified OMC Cobra V6 and V8 applications.
- Includes one thermostat, one gasket, and one O-ring.
- Aftermarket replacement; not an original equipment component.
Part Number References
The following references are associated with this thermostat kit or its included components. Use the complete application information below rather than relying on a number alone.
| Reference Type | Part Number | Description |
|---|---|---|
| OMC replacement reference | 3856961 | Thermostat |
| OEM reference | 0383307 | Thermostat kit reference |
| OEM reference | 3852216 | Thermostat kit reference |
| Aftermarket reference | 18-3677D | 160°F thermostat kit reference |
Engine Compatibility
This kit is listed for the following OMC Cobra applications. Model, year, and engine configuration must match your engine identification and service documentation.
| Brand | Engine Model | Years | Engine Configuration | Thermostat Reference |
|---|---|---|---|---|
| OMC Cobra | 4.3L | 1994–1997 | V6 gasoline marine engine | 3856961 |
| OMC Cobra | 4.3 HO | 1991–1997 | High-output V6 gasoline marine engine | 3856961 |
| OMC Cobra | 5.0L | 1994–1997 | V8 gasoline marine engine | 3856961 |
| OMC Cobra | 5.8L | 1994–1997 | V8 gasoline marine engine | 3856961 |
| OMC Cobra | 5.8 EFI | 1993–1997 | Electronic-fuel-injection V8 gasoline marine engine | 3856961 |
Important: The company application data for this kit identifies OMC Cobra applications only. The previous broad Volvo Penta compatibility claims have been removed. Do not assume fitment for other Volvo Penta, OMC, or four-cylinder engines without confirming the exact engine and thermostat reference.
Technical Specifications
- Product Type
- Thermostat kit
- Thermostat Rating
- 160°F (71°C)
- Application
- Specified OMC Cobra marine gasoline engines
- Engine Types
- 4.3L V6, 4.3 HO V6, 5.0L V8, 5.8L V8, and 5.8 EFI V8 applications as listed
- Installation Type
- Replacement thermostat service
- Construction
- Aftermarket replacement components
What's in the Box
- 1 x 160°F thermostat — replaces reference 3856961
- 1 x thermostat gasket — component reference 3852111
- 1 x O-ring — component reference 3852071
Installation Notes
Thermostat replacement procedures vary by engine and cooling system. Always follow the service manual for your specific OMC Cobra engine.
- Disconnect the battery and allow the engine to cool completely.
- Close or disconnect the water supply as required by the engine and service procedure.
- Locate the thermostat housing and place a suitable container beneath the work area.
- Remove the housing cover and retain the fasteners in their original locations.
- Remove the old thermostat, gasket, and O-ring.
- Clean the mating surfaces carefully, removing old gasket material without damaging the housing.
- Install the new thermostat in the correct orientation with the supplied gasket and O-ring.
- Reinstall the housing cover and tighten the fasteners to the manufacturer's specified torque.
- Restore the cooling-system connections or water supply according to the service manual.
- Start the engine, allow it to reach operating temperature, and check for leaks and proper temperature regulation.
Troubleshooting & FAQ
What does a failing marine thermostat do?
A thermostat stuck closed can contribute to overheating, while a thermostat stuck open can prevent the engine from reaching its intended operating temperature. Erratic temperature readings or leakage around the thermostat housing may also indicate a service issue.
Is this a 160°F thermostat?
Yes. This kit is specified as a 160°F (71°C) thermostat kit. Use the temperature rating required by your engine's service documentation.
Will this kit fit any Volvo Penta or OMC engine?
No. The company application data identifies the OMC Cobra 4.3L, 4.3 HO, 5.0L, 5.8L, and 5.8 EFI applications and years listed on this page. Confirm your exact engine model and part reference before purchase.
Does the kit include the gasket and O-ring?
Yes. The kit includes one 160°F thermostat, one thermostat gasket, and one O-ring.
Is this an OEM thermostat kit?
No. This is an aftermarket replacement kit intended for the specified OMC Cobra applications. The listed OEM and aftermarket numbers are reference numbers used for identification and compatibility checking.
Do I need sealant during installation?
Use sealant only if the engine manufacturer's service procedure specifically calls for it. Do not apply sealant to the thermostat or O-ring unless instructed by the service manual.
Safety & Important Information
- Verify the engine model, year, configuration, cooling system, and existing thermostat reference before ordering.
- Allow the engine to cool completely before opening the thermostat housing.
- Follow the engine service manual for torque values, gasket orientation, cooling-system procedures, and testing.
- Professional installation is recommended when the cooling system or engine application is uncertain.
About Sea Sierra
- Marine Replacement Parts — Parts selected for specified marine service applications.
- Application-Focused Listings — Product information is organized around engine model and year conditions.
- Service-Ready Kits — Includes the thermostat, gasket, and O-ring needed for the listed thermostat service.
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