140°F Thermostat Kit – Fits OMC Cobra/Volvo Penta 7.4L/8.1L/8.2L V6/V8 (Replaces 3853983, 312797, 307239)

140°F Thermostat Kit – Fits OMC Cobra/Volvo Penta 7.4L/8.1L/8.2L V6/V8

This marine thermostat kit is designed for OMC Cobra and Volvo Penta stern drives with 7.4L, 8.1L, and 8.2L engines (1993-current). It is engineered to maintain a consistent engine operating temperature of 140°F (60°C) for optimal performance and longevity.

This kit serves as a direct replacement for OMC part numbers 3853983, 312797, and 307239, as well as Volvo Penta numbers 3853983, 3852071, and 835417.

• Operating Temperature: Maintains a stable 140°F (60°C).
• Engine Compatibility: Fits select OMC Cobra and Volvo Penta V6/V8 engines.
• Complete Assembly: Includes the thermostat, gasket, and O-ring for a full replacement.

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below.

Technical Specifications

Package Contents

• 1 x Thermostat (3853983, 09886506)
• 1 x Thermostat Gasket (835417, 18-0398)
• 1 x O-Ring (3852071, 18-7170)

Installation Guide

1. Ensure the engine is completely cool before starting.
2. Drain the engine coolant into a suitable container.
3. Locate the thermostat housing on the engine block.
4. Carefully remove the bolts securing the housing.
5. Remove the old thermostat and gasket. Note the orientation of the thermostat.
6. Clean both the housing and engine mounting surfaces thoroughly.
7. Install the new gasket and thermostat in the correct position. The spring side usually faces the engine.
8. Replace the thermostat housing and tighten the bolts to the manufacturer's specified torque.
9. Refill the cooling system with the appropriate coolant.
10. Start the engine and check for leaks around the housing as the engine warms up.
11. Once the engine reaches operating temperature, top off the coolant level if necessary.

Troubleshooting & FAQ

Q: How do I confirm this thermostat kit will fit my engine?

A: The best way is to verify your engine model and year against the "Compatible Engine Models" chart. You can also match the part numbers listed in the "Part Number Cross-Reference" table with your existing thermostat or service manual.

Q: What are the symptoms of a faulty thermostat?

A: Common signs include the engine overheating (running too hot) or failing to reach its normal operating temperature (running too cold). Both can negatively impact performance and fuel economy.

Q: Is this thermostat for raw water or freshwater cooling systems?

A: This kit is suitable for both fresh water and salt water cooled engines.

Q: OEM vs. Aftermarket?

A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?

A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?

A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.