Thermostat Repair Kit – Fits OMC Cobra 120/140, Volvo Penta 2.5L & 3.0L (Replaces 3853799, 982554)
Thermostat Repair Kit – Fits OMC Cobra 120/140, Volvo Penta 2.5L & 3.0L (Replaces 3853799, 982554) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Thermostat Repair Kit – Fits OMC Cobra 120/140, Volvo Penta 2.5L &a...
Product Details
This Thermostat Repair Kit is designed for OMC Cobra and Volvo Penta sterndrive engines. It provides a reliable fix for cooling system issues, fitting specific OMC models from 1980–1998 (including 120/140HP, 2.5L, and 3.0L) and various Volvo Penta 3.0L GLP, GLM, GSM, and GSP models.
This kit serves as a direct replacement for OMC part numbers 3853799, 982554, and 778064, as well as Sierra 18-3670 and GLM 13440.
- Engineered for direct OEM replacement installation.
- Maintains optimal engine temperature with a 160°F (71°C) rating.
- Includes all necessary gaskets for a complete thermostat replacement.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| OMC | 3853799 / 982554 / 778064 |
| Sierra | 18-3670 |
| GLM | 13440 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Fits OMC Cobra and Sterndrive models from 1980 to 1998.
Fits various 4-cylinder Volvo Penta 3.0L models from 1968 and newer.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| OMC | Cobra | 120 | 4-Stroke | 1980–1981 | 3853799 | Also known as 982554 |
| OMC | Cobra | 140 | 4-Stroke | 1980–1981 | 3853799 | Also known as 982554 |
| OMC | Sterndrive | 2.5L (252ci) | 4-Stroke | 1982–1986 | 3853799 | Also known as 982554 |
| OMC | Sterndrive | 3.0L (302ci) | 4-Stroke | 1982–1998 | 3853799 | Also known as 982554 |
| Volvo Penta | 3.0GLP | 4-Stroke | Fits 4 cylinder models 1968 and newer | |||
| Volvo Penta | 3.0GLM | 4-Stroke | Fits 4 cylinder models 1968 and newer | |||
| Volvo Penta | 3.0GSM | 4-Stroke | Fits 4 cylinder models 1968 and newer | |||
| Volvo Penta | 3.0GSP | 4-Stroke | Fits 4 cylinder models 1968 and newer |
Technical Specs
- Product Type
- Thermostat Repair Kit
- Installation
- Direct OEM replacement
- Temperature Rating
- 160°F (71°C)
- Application
- Marine sterndrive engines
- Other Technical Attributes
- Includes thermostat and housing gaskets
What’s in the Box
- 1 x Thermostat (3853799/982554/7778064)
- 1 x Thermostat Housing Cover Gasket (314809/3852127/777906)
- 1 x Thermostat Gasket (313416/3852120/777848)
Installation Notes
- Disconnect the battery and allow the engine to cool completely.
- Drain the engine coolant into a suitable container.
- Locate the thermostat housing and remove the bolts securing the cover.
- Remove the old thermostat and gasket. Note the orientation of the thermostat.
- Thoroughly clean the gasket mating surfaces on both the housing and cover.
- Install the new thermostat in the correct orientation.
- Place the new gaskets and reinstall the housing cover, tightening bolts to the manufacturer's specification.
- Refill the cooling system with the appropriate coolant.
- Reconnect the battery, start the engine, and check for any leaks around the housing. Monitor the temperature gauge to ensure normal operation.
Troubleshooting & FAQ
How do I know if my thermostat is failing?
Common signs include the engine overheating, running too cool (not reaching operating temperature), erratic temperature gauge readings, or coolant leaks around the thermostat housing.
Is this the correct temperature rating for my engine?
This kit includes a 160°F (71°C) thermostat, which is the standard rating for many raw water cooled OMC and Volvo Penta engines. However, always confirm your engine’s service manual for the specific temperature requirement.
Can I reuse my old housing gaskets?
No. Always use the new gaskets included in the kit to ensure a proper, leak-free seal. Gaskets are designed for single use and compress permanently upon installation.
What are the signs of an incorrect installation?
The most common signs are coolant leaks from the housing, engine overheating (if the thermostat is installed backward or gets stuck), or the engine failing to warm up properly.
How often should a marine thermostat be replaced?
There is no fixed interval, but it is good practice to inspect it annually and consider replacement every 3-5 years as preventative maintenance, especially if operating in saltwater.
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.
Payment & Security
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