Thermostat Kit 160°F – Fits OMC Cobra & Volvo Penta 3.8L-7.5L V6/V8 (Replaces 383307, 3856961)

$24.50

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Thermostat Kit 160°F – Fits OMC Cobra & Volvo Penta 3.8L-7.5L V6/V8 (Replaces 383307, 3856961) is backordered and will ship as soon as it is back in stock.

Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

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 Marine Thermostat Kit 160°F is a complete replacement kit for OMC Cobra and Volvo Penta marine engines. It includes a 160°F (71°C) thermostat and all gaskets necessary for installation on V6 and V8 engines, including OMC Cobra models from 1969–1988 (3.8L-7.5L) and various Volvo Penta 4.3L, 5.0L, 5.7L, and 5.8L sterndrive models.

This kit serves as a direct cross-reference for OMC parts 379754, 383307, 3852216, 3856961; Volvo Penta 3856961; Sierra 18-3653/18-3554; GLM 13430/13060; and Mallory 9-43156/9-43021.

Engineered for direct OEM-replacement fitment.
Maintains a consistent 160°F (71°C) operating temperature.
Includes thermostat and all required gaskets 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	3852216
OMC	3856961
Volvo Penta	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.

Fits a wide range of OMC Cobra Sterndrive and Marine Engines produced between 1969 and 1988.

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

Compatible with various Volvo Penta Four-Stroke V6 and V8 marine engines.

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
Temperature Rating: 160°F (71°C)
Installation: Direct OEM replacement
Housing Color: Silver/metallic
Weight: 2.82 oz (0.08 kg)
Application: Small thermostat applications in OMC and Volvo Penta engines
Production Standard: ISO9002 certified factory
Warranty: Manufacturer warranty (varies by supplier)

What’s in the Box

1 x Thermostat (383307)
1 x O-ring (3852071)
1 x Gasket (314809)
1 x Gasket (313416)
1 x Housing Gasket (3852111)
1 x Installation Instructions (when included by manufacturer)

Installation Notes

Disconnect the battery terminals to ensure safety.
Place a catch pan under the engine and drain the coolant below the level of the thermostat housing.
Locate the thermostat housing and remove the bolts or nuts securing it.
Gently tap the housing to break the seal and remove it. Take note of the old thermostat's orientation.
Remove the old thermostat and all gasket material from both the housing and the engine mating surfaces.
Install the new thermostat in the correct orientation.
Place the new gaskets and O-rings as required by your specific engine model.
Reinstall the thermostat housing and tighten the fasteners to the manufacturer's recommended torque.
Refill the cooling system with the appropriate coolant mixture.
Reconnect the battery, start the engine, and let it warm up. Check carefully for any leaks around the housing.

Troubleshooting & FAQ

How do I confirm this thermostat fits my engine?

The best way is to cross-reference your existing part number with our Part Number Matrix. Additionally, check your engine model and year against the compatibility tables. If you are unsure, please consult your service manual or a professional marine mechanic.

What are the signs of a faulty thermostat?

Common symptoms include engine overheating (reading high on the temp gauge), the engine not reaching operating temperature (running too cool), or large, sudden fluctuations in temperature. Leaking coolant around the thermostat housing is also an indicator.

Can I use a different temperature thermostat?

It's highly recommended to use the temperature rating specified by your engine's manufacturer (160°F for this kit). Using a hotter or colder thermostat can affect engine performance, fuel efficiency, and longevity.

How often should a marine thermostat be replaced?

Thermostats don't have a fixed replacement interval, but they are a common wear item. It is good practice to inspect them during routine cooling system service or replace them every few hundred hours or every few years, especially if operating in saltwater.

Is this an OEM part?

This is a high-quality aftermarket replacement, not an OEM component. It is designed and manufactured to meet or exceed OEM specifications for fit, form, and function, produced in an ISO 9002 certified facility to ensure quality and reliability.

What are your shipping speeds and costs?

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free for most orders, with expedited options available at checkout where applicable.

What is the warranty and return policy?

This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their original condition.

Safety & Important Info

Verify images and specifications against your original part before purchase. If anything differs—even if your model is listed as compatible—do not order.
This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
Professional installation is highly recommended for safety, performance, and to prevent engine damage.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world reliability.
Fast Global Fulfillment — We offer free standard delivery to most regions, with an average transit time of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

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