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

$19.97

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Thermostat Kit 160°F – Fits OMC Cobra & Volvo Penta 4.3L-5.8L V6/V8 (Replaces 383307, 3856961) is backordered and will ship as soon as it is back in stock.

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Thermostat Kit 160°F is an essential component for maintaining optimal engine temperature in a wide range of OMC Cobra and Volvo Penta marine engines. It fits OMC Cobra 3.8L to 7.5L V6/V8 sterndrive models (1969–1993) and various Volvo Penta four-stroke V6/V8 engines, including the GL, GS, Gi, FL, Fi, and FSi series.

This kit serves as a direct replacement for multiple OEM and aftermarket part numbers, including OMC 383307/3856961, Sierra 18-3653, GLM 13060, and Mallory 9-43021.

Engineered for direct OEM replacement fit and function.
Maintains a consistent 160°F (71°C) operating temperature.
Kit includes the thermostat, gasket, and O-ring for a complete installation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
OMC	379754
OMC	383307
OMC	3856961
Sierra	18-3653
Sierra	18-3554
GLM	13430
GLM	13060
Mallory	9-43156
Mallory	9-43021

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For OMC Cobra Sterndrive & Marine Engines, this thermostat fits a wide range of models from 1969 to 1993. Verify your engine's specific model and year against the chart.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
OMC	3.8L	80-120	4-Stroke	1981–1985	383307	Small thermostat version
OMC	4.3L	120-205	4-Stroke	1985–1986	383307	Small thermostat version
OMC	5.0L	140-230	4-Stroke	1982–1988	383307	Small thermostat version
OMC	5.7L	175-260	4-Stroke	1982–1988	383307	Small thermostat version
OMC	7.5L	320-330	4-Stroke	1982–1988	383307	Small thermostat version
OMC	90	90	4-Stroke	1970	383307	Outdrive model
OMC	100	100	4-Stroke	1972–1973	383307	Outdrive model
OMC	120	120	4-Stroke	1969–1980	383307	Outdrive model
OMC	140	140	4-Stroke	1973–1980	383307	Outdrive model
OMC	155	155	4-Stroke	1969–1972	383307	Outdrive model
OMC	165-175	165-175	4-Stroke	1972–1977	383307	Outdrive models
OMC	185-200	185-200	4-Stroke	1978–1981	383307	Outdrive models
OMC	210-245	210-245	4-Stroke	1969–1975	383307	Outdrive models
OMC	250-260	250-260	4-Stroke	1970–1981	383307	Outdrive models
OMC	305-454	305-454	4-Stroke	1977–1982	383307	Outdrive models
OMC	Cobra 4.3L	120-205	4-Stroke	1986–1993	3856961	Small thermostat version

For Volvo Penta Marine Engines, this part is compatible with select V6 and V8 models. Confirm the correct OEM part number for your application.

Brand	Model	Rated HP	Stroke	OEM Part No.	Notes
Volvo Penta	4.3GL/GS/Gi	140-225	4-Stroke	3856961	V6 Engine
Volvo Penta	5.0FL/Fi	170-220	4-Stroke	3856961	V8 Engine
Volvo Penta	5.7GL/Gi	200-280	4-Stroke	3856961	V8 Engine
Volvo Penta	5.8FL/Fi/FSi	200-300	4-Stroke	3856961	V8 Engine
Volvo Penta	V6-200/225/225E	200-225	4-Stroke	3856961	V6 Engine
Volvo Penta	V8-225/270/300/320/380	225-380	4-Stroke	3856961	V8 Engine

Technical Specs

Product Type: Marine Engine Thermostat Kit
Installation: Direct OEM replacement
Temperature Rating: 160°F (71°C)
Fuel Type: Gasoline
Housing Material: Brass/metal
Housing Color: Silver/metallic
Weight: 2.82 oz (0.08 kg)
Operating Temperature: 160°F (71°C) opening temperature
Other Technical Attributes: Small thermostat version
Warranty: Manufacturer warranty (varies by supplier)

What’s in the Box

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

Installation Notes

Ensure the engine is completely cool before beginning. Disconnect the battery for safety.
Locate the thermostat housing on the engine, typically where the main coolant hose connects.
Place a drain pan under the housing and slowly loosen the bolts to drain the coolant.
Remove the old thermostat, gasket, and O-ring. Note the orientation of the old thermostat.
Thoroughly clean the mating surfaces of the housing to remove any old gasket material or corrosion.
Install the new thermostat in the same orientation as the original, followed by the new gasket and O-ring.
Tighten the housing bolts to the manufacturer's specified torque. Do not overtighten.
Reconnect the hose, refill the cooling system, and check for leaks before starting the engine.

Troubleshooting & FAQ

How do I know if my thermostat has failed?

Common signs of a faulty thermostat include engine overheating (stuck closed) or taking too long to reach operating temperature (stuck open). You may notice your temperature gauge reading abnormally high or low after the engine has been running for a while.

What's the difference between a 160°F thermostat and others?

The 160°F rating indicates the temperature at which the thermostat begins to open. This is crucial for engines used in raw water (lake, river, ocean) cooling systems to prevent salt and mineral buildup that can occur at higher temperatures. Using the correct temperature rating is vital for engine longevity.

Is this thermostat for raw-water or freshwater cooled engines?

A 160°F thermostat is standard for raw-water (sea-water) cooled marine engines. Freshwater (closed cooling) systems typically use higher temperature thermostats (e.g., 180°F–195°F), similar to automotive engines. Always use the temperature rating specified by your engine manufacturer.

What does "small thermostat version" mean?

This refers to the physical size of the thermostat itself. Over the years, manufacturers sometimes used different sized thermostats in their housings. This kit is for applications requiring the "small" version, as specified for the listed OMC models. Always compare the new part to your old one before installation.

How often should I replace my marine thermostat?

As a preventative maintenance item, it is recommended to inspect your thermostat annually and replace it every 3-5 years, or immediately if you notice signs of failure. In saltwater environments, more frequent replacement may be necessary due to corrosion.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns?

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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