Thermostat Kit 160°F – Fits OMC Cobra & Volvo Penta 4.3L-5.8L V6/V8 Marine Engines (Replaces 383307, 3856961)

Thermostat Kit 160°F – Fits OMC Cobra & Volvo Penta 4.3L-5.8L V6/V8 Marine Engines (Replaces 383307, 3856961)

This thermostat kit is designed for a wide range of OMC Cobra and Volvo Penta marine engines. It ensures your engine maintains the correct operating temperature for optimal performance and longevity. It is compatible with OMC Cobra V6 and V8 sterndrive models (1969–1993) and Volvo Penta four-stroke V6/V8 engines (4.3L, 5.0L, 5.7L, 5.8L) across the GL, GS, Gi, FL, Fi, and FSi series.

This component is a direct replacement for several OEM and aftermarket part numbers, including OMC 379754, 383307, and 3856961; Sierra 18-3653 and 18-3554; GLM 13430 and 13060; and Mallory 9-43156 and 9-43021.

• Complete Kit: Includes the thermostat, gasket, and O-ring for a full replacement.
• Precise Temperature Control: Maintains a consistent engine temperature of 160°F (71°C).
• Easy Installation: Designed as a direct OEM replacement for a straightforward installation process.

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.

OMC Cobra (Sterndrive & Marine Engines)

Volvo Penta Marine Engines

Technical Specifications

Package Contents

• 1 x 160°F Thermostat (Replaces 383307, 3856961)
• 1 x Gasket (Replaces 3852111)
• 1 x O-Ring (Replaces 3852071)

Installation Guide

1. Safety First: Disconnect the battery and ensure the engine is completely cool before starting.
2. Drain Coolant: Place a catch pan under the engine drain plug and drain the coolant below the level of the thermostat housing.
3. Locate Housing: Find the thermostat housing, typically located where the top radiator hose connects to the engine.
4. Remove Housing: Loosen and remove the bolts securing the housing cover. Gently tap it if it is stuck, but do not pry it open.
5. Remove Old Parts: Take out the old thermostat, gasket, and any O-rings. Note the orientation of the thermostat.
6. Clean Surfaces: Thoroughly clean the mating surfaces of the housing and engine block to remove any old gasket material or corrosion.
7. Install New Parts: Place the new thermostat into the engine, ensuring it is oriented correctly. Position the new gasket and O-ring.
8. Reassemble: Re-install the housing cover and tighten the bolts to the manufacturer's specified torque. Do not overtighten.
9. Refill and Check: Refill the cooling system with the appropriate coolant. Start the engine and let it warm up, checking carefully for any leaks around the housing.

Troubleshooting & FAQ

Q: How do I know if this thermostat kit fits my OMC or Volvo Penta engine?

A: First, check the compatible engine model tables on this page to ensure your specific model and year are listed. Second, verify that the OEM part numbers listed—383307 or 3856961—match what is specified for your engine in your service manual. Note that this is the small thermostat version.

Q: What are the signs of a failing thermostat?

A: Common signs include the engine overheating, the engine running too cool and never reaching its proper operating temperature, erratic temperature gauge readings, and poor engine performance or fuel economy.

Q: How often should I replace my marine thermostat?

A: It is recommended to inspect your thermostat annually and consider replacing it every 2-3 years as part of preventative maintenance, especially for engines operated in saltwater. Replace it immediately if you notice any signs of failure.

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.