Aftermarket Vernatherm Thermostat for Johnson/Evinrude 3- and 4-Cylinder Outboards, 1985–1990 — Replaces 384719, 0384719 and 0777838
Aftermarket Vernatherm Thermostat for Johnson/Evinrude 3- and 4-Cylinder Outboards, 1985–1990 — Replaces 384719, 0384719 and 0777838 is backordered and will ship as soon as it is back in stock.
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Aftermarket Vernatherm Thermostat for Johnson/Evinrude 3- and 4-Cyl...
Aftermarket Vernatherm Thermostat for Johnson/Evinrude 3- and 4-Cylinder Outboards, 1985–1990 — Replaces 384719, 0384719 and 0777838 is backordered and will ship as soon as it is back in stock.
Product Details
This is an aftermarket Vernatherm thermostat for most 3- and 4-cylinder Johnson/Evinrude outboard applications from 1985 through 1990. It is designed to help the engine maintain its intended operating temperature during normal use.
The thermostat replaces Johnson/Evinrude/OMC references 384719, 0384719 and 0777838. It is also listed as an interchange for Sierra Marine 18-3560. The company specification identifies the standard Vernatherm rating as 105°F (40.5°C), with an actual operating temperature of 143°F (62°C).
- Aftermarket replacement Vernatherm thermostat.
- Fits most 3- and 4-cylinder Johnson/Evinrude outboards within the listed application range.
- Standard rating: 105°F (40.5°C).
- Actual operating temperature specification: 143°F (62°C).
- Sold as one thermostat; gasket or seal is not included.
Part Number Matrix
Use these references to compare the thermostat with the part being replaced. Confirm the engine application before ordering.
| Brand or Reference | Part Number | Reference Type |
|---|---|---|
| Johnson/Evinrude/OMC | 384719 | OEM replacement reference |
| Johnson/Evinrude/OMC | 0384719 | OEM replacement reference |
| Johnson/Evinrude/OMC | 0777838 | OEM replacement reference |
| Sierra Marine | 18-3560 | Aftermarket interchange reference |
| OMC/BRP or Mallory reference | BRP9-43027 | Additional reference listed by the supplier |
Engine & Model Compatibility
This thermostat is listed for most 3- and 4-cylinder Johnson/Evinrude outboards manufactured from 1985 through 1990. The application information below is a guide; exact fitment may depend on the complete engine model and serial-number range.
| Brand | Application | Rated HP | Stroke | Years | OEM Reference | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | 3- and 4-cylinder outboards | Most applications | Not specified | 1985–1990 | 384719 / 0384719 / 0777838 | Supplier-listed general application; verify the complete model and serial number. |
| Johnson/Evinrude | 60, 125 and 185 hp applications | 60 / 125 / 185 | Not specified | 1989–1990 | 384719 | Application listed in the Sierra reference catalog. |
| Johnson/Evinrude | 65 hp applications | 65 | Not specified | 1987–1989 | 384719 | Application listed in the Sierra reference catalog. |
| Johnson/Evinrude | 70, 200 and 225 hp applications | 70 / 200 / 225 | Not specified | 1986–1990 | 384719 | Application listed in the Sierra reference catalog. |
| Johnson/Evinrude | 120, 140 and 300 hp applications | 120 / 140 / 300 | Not specified | 1985–1990 | 384719 | Application listed in the Sierra reference catalog. |
| Johnson/Evinrude | 275 hp applications | 275 | Not specified | 1985–1988 | 384719 | Application listed in the Sierra reference catalog. |
Technical Specs
- Product Type
- Vernatherm thermostat
- Product Configuration
- Single thermostat; not a kit
- Application
- Most 3- and 4-cylinder Johnson/Evinrude outboards, 1985–1990
- Standard Rating
- 105°F (40.5°C)
- Actual Operating Temperature
- 143°F (62°C)
- OEM Replacement References
- 384719, 0384719 and 0777838
- Aftermarket Interchange
- Sierra Marine 18-3560
What’s in the Box
- 1 x Vernatherm thermostat
A thermostat gasket, housing gasket or seal is not included. Replace the seal or gasket as required for the specific engine application.
Installation Notes
- Confirm the replacement reference and complete engine model before installation.
- Make sure the engine is completely cool and follow the service manual safety procedure.
- Locate the thermostat housing and place a suitable drain pan beneath the work area.
- Remove the housing cover carefully, keeping track of fastener locations.
- Remove the old thermostat and all deteriorated gasket or seal material.
- Clean the mating surfaces without damaging the housing or cylinder-head sealing area.
- Install the new thermostat in the same orientation as the original part.
- Install the correct new gasket or seal for the engine application; it is sold separately.
- Reinstall the housing cover and tighten the fasteners to the engine manufacturer’s specified torque.
- Restore the cooling system as required, start the engine, and check for proper water flow and leaks.
Troubleshooting & FAQ
What temperature is this thermostat rated for?
The supplier lists a standard Vernatherm rating of 105°F (40.5°C) and an actual operating temperature specification of 143°F (62°C).
What engines does this thermostat fit?
It is listed for most 3- and 4-cylinder Johnson/Evinrude outboards in the 1985–1990 application range. Because applications can vary by model and serial number, compare the original thermostat and verify the complete engine identification before ordering.
Is this a complete thermostat kit?
No. This listing is for one thermostat only. A thermostat gasket, housing gasket or seal is not included.
Does this fit V4 or V6 cross-flow engines?
The supplier describes this product for most 3- and 4-cylinder applications. Do not assume fitment for a V4 or V6 engine unless the complete engine model and serial-number information confirms the application.
What are common signs of a faulty thermostat?
Possible symptoms include slow warm-up, abnormal operating temperature, overheating, or inconsistent cooling-system performance. Diagnose the complete cooling system before replacing the thermostat.
Is this an OEM thermostat?
No. This is an aftermarket replacement for the listed Johnson/Evinrude/OMC references.
Safety & Important Info
- Verify the complete engine model, year and serial-number range before purchase.
- Compare the replacement part with the original thermostat, including its shape and sealing arrangement.
- Do not install or remove cooling-system components while the engine is hot.
- This is an aftermarket replacement, not an OEM component.
- Professional installation is recommended when the correct application or installation procedure is uncertain.
About Sea Sierra
- Marine Replacement Parts — Practical aftermarket components for common outboard service needs.
- Application-Focused Listings — Reference numbers and application information are provided to help with part comparison.
- Fitment Guidance — Always verify the complete engine identification before installation.
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