Thermostat Kit for OMC Cobra and Volvo Penta 4.3L–5.8L V6/V8 Engines — Replaces 383307, 18-3653 and 3856961
Thermostat Kit for OMC Cobra and Volvo Penta 4.3L–5.8L V6/V8 Engines — Replaces 383307, 18-3653 and 3856961 is backordered and will ship as soon as it is back in stock.
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Thermostat Kit for OMC Cobra and Volvo Penta 4.3L–5.8L V6/V8 Engine...
Thermostat Kit for OMC Cobra and Volvo Penta 4.3L–5.8L V6/V8 Engines — Replaces 383307, 18-3653 and 3856961 is backordered and will ship as soon as it is back in stock.
Product Details
This marine engine thermostat kit is designed for selected OMC Cobra and Volvo Penta sterndrive applications using 4.3L–5.8L V6 and V8 engines. The kit uses a 160°F (71°C) thermostat and includes the gaskets and O-ring needed for the applicable thermostat housing configuration.
It is commonly cross-referenced with OMC, Volvo Penta, Sierra, GLM and Mallory replacement numbers listed below. Fitment can vary by engine model, cooling-system design and production year, so compare the original thermostat, housing and part numbers before ordering.
- 160°F (71°C) marine thermostat
- For selected OMC Cobra and Volvo Penta 4.3L–5.8L V6/V8 applications
- Kit includes multiple gasket options and an O-ring for applicable installations
- Aftermarket replacement for the listed reference numbers
Part Number Matrix
Use the following references to compare the replacement kit with the number shown on your original part or engine documentation. These references should not be treated as universal fitment without confirming the complete engine and cooling-system application.
| Brand | Reference Number |
|---|---|
| OMC | 379754 |
| OMC | 383307 |
| OMC | 3856961 |
| Volvo Penta | 3856961 |
| Sierra | 18-3653 |
| Sierra | 18-3554 |
| GLM | 13430 |
| GLM | 13060 |
| Mallory | 9-43156 |
| Mallory | 9-43021 |
Engine and Model Compatibility
This kit is intended for selected OMC Cobra and Volvo Penta marine engines in the 4.3L–5.8L range. The application examples below are provided as reference points; always confirm the exact engine model, year, serial range and thermostat-housing configuration before installation.
| Brand | Application Family | Engine Size | Reference Number | Fitment Note |
|---|---|---|---|---|
| OMC Cobra | 3.8L V6 | 3.8L | 383307 | Verify the original thermostat and housing before ordering. |
| OMC Cobra | 4.3L V6 / 4.3HO | 4.3L | 383307 or 3856961 | Model and production-year conditions may apply. |
| OMC Cobra | 5.0L V8 | 5.0L | 383307 or 3856961 | Confirm the engine-specific cooling-system configuration. |
| OMC Cobra | 5.7L V8 | 5.7L | 383307 or 3856961 | Confirm the original reference number before purchase. |
| OMC Cobra | 5.8L V8 / 5.8EFI | 5.8L | 3856961 | Verify model, year and serial range. |
| Volvo Penta | 4.3GL, 4.3GS and 4.3Gi | 4.3L | 3856961 | Verify the thermostat housing and original part number. |
| Volvo Penta | 5.0FL and 5.0Fi | 5.0L | 3856961 | Verify the exact engine and cooling-system configuration. |
| Volvo Penta | 5.7GL and 5.7Gi | 5.7L | 3856961 | Verify the original reference number before installation. |
| Volvo Penta | 5.8FL, 5.8Fi and 5.8FSi | 5.8L | 3856961 | Verify model, year and serial range. |
Technical Specifications
- Product Type
- Marine engine thermostat kit
- Thermostat Rating
- 160°F (71°C)
- Intended Applications
- Selected OMC Cobra and Volvo Penta 4.3L–5.8L V6/V8 marine engines
- Installation
- Replacement installation; confirm the correct gasket and O-ring arrangement for the engine
- Seal Type
- O-ring and gasket sealing components included
- Housing Material
- Not specified for this replacement kit
What's in the Box
- 1 × 160°F thermostat
- 1 × thermostat housing gasket
- 1 × O-ring
- 1 × additional gasket option
- 1 × additional gasket option
Gasket selection depends on the specific engine and thermostat-housing design. Do not install every gasket in the kit unless the engine service instructions require it.
Installation Notes
- Allow the engine to cool completely and follow the engine manufacturer's safety instructions.
- Disconnect the battery and drain or lower the coolant level as required for the thermostat housing.
- Remove the hoses and thermostat-housing cover according to the engine service manual.
- Note the orientation of the original thermostat before removal.
- Remove the old thermostat, gasket and O-ring, then clean the mating surfaces carefully.
- Install the new thermostat in the correct orientation.
- Select and install the gasket and O-ring that match the engine's housing configuration.
- Reinstall the housing and tighten the fasteners to the manufacturer's specified torque.
- Reconnect the hoses, refill the cooling system as applicable and reconnect the battery.
- Run the engine while monitoring temperature and checking for leaks.
Use the applicable factory service information for torque values, coolant procedures and any model-specific sealing requirements.
Troubleshooting and FAQ
What are common signs of a failing thermostat?
Possible symptoms include overheating, operating below the normal temperature range, unstable temperature readings or coolant leakage around the thermostat housing. Other cooling-system faults can produce similar symptoms, so inspect the complete system before replacing the thermostat.
Is the 160°F thermostat correct for my engine?
This kit is specified with a 160°F (71°C) thermostat for the listed applications. Confirm the required temperature rating and reference number in your engine documentation before installation.
Why are several gaskets included?
The kit includes gasket options for different applicable housing configurations. The correct gasket depends on the engine and housing design; unused gasket options should be retained as spares and should not be stacked or substituted without service-manual guidance.
Do I need sealant?
Use the gasket and O-ring as specified by the engine manufacturer. Do not apply sealant unless the service instructions specifically permit it, because excess sealant can interfere with sealing or enter the cooling passage.
Is this an OEM part?
This listing is for an aftermarket replacement kit. The numbers shown are manufacturer or aftermarket reference numbers used to help compare the replacement with the original application.
How should I confirm fitment?
Compare the original thermostat and housing, the engine model, year, serial range and the complete reference number. If any of these details differ, confirm the application with the engine service information before ordering.
Safety and Important Information
- Work only on a completely cool engine to reduce the risk of burns.
- Confirm fitment using the complete engine model, year, serial range and original part number.
- Follow the applicable service manual for coolant handling, torque specifications and bleeding procedures.
- Professional installation is recommended when the cooling-system procedure or engine configuration is unfamiliar.
About Sea Sierra
- Marine Replacement Parts — Replacement components for selected marine engine and sterndrive applications.
- Application-Focused Listings — Reference numbers and compatibility information are provided to help compare the replacement with the original part.
- Fitment First — Always verify the exact engine and cooling-system configuration before installation.
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