Thermostat – Fits Johnson/Evinrude 85-135 HP (Replaces 384719, 0384719, 0777838)
Thermostat – Fits Johnson/Evinrude 85-135 HP (Replaces 384719, 0384719, 0777838) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
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Thermostat – Fits Johnson/Evinrude 85-135 HP (Replaces 384719, 0384...
Thermostat – Fits Johnson/Evinrude 85-135 HP (Replaces 384719, 0384719, 0777838) is backordered and will ship as soon as it is back in stock.
Product Details
This is an aftermarket Thermostat – Fits Johnson/Evinrude 85-135 HP for 2-stroke, 4-cylinder cross-flow engines manufactured between 1973 and 1978. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.
It serves as a direct interchange for Johnson/Evinrude part numbers 384719, 0384719, and 0777838, as well as Sierra 18-3560 and WSM 775-101.
- Engineered for direct OEM-replacement installation.
- Constructed from a durable brass and metal alloy.
- Opens at a consistent 143°F (62°C) operating temperature.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Johnson/Evinrude | 384719 / 0384719 / 0777838 |
| Sierra | 18-3560 |
| WSM | 775-101 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This part is designed exclusively for the following Johnson/Evinrude engines.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Johnson/Evinrude | 4 Cyl, 3.375" Bore Cross Flow | 85 | 2-Stroke | 1973–1978 | 384719/0384719 | |
| Johnson/Evinrude | 4 Cyl, 3.500" Bore Cross Flow | 100 | 2-Stroke | 1971–1972 | 384719/0384719 | |
| Johnson/Evinrude | 4 Cyl, 3.500" Bore Cross Flow | 115 | 2-Stroke | 1973–1977 | 384719/0384719 | |
| Johnson/Evinrude | 4 Cyl, 3.500" Bore Cross Flow | 125 | 2-Stroke | 1971–1972 | 384719/0384719 | |
| Johnson/Evinrude | 4 Cyl, 3.500" Bore Cross Flow | 135 | 2-Stroke | 1973–1976 | 384719/0384719 |
Technical Specs
- Product Type
- Thermostat
- Installation
- Direct OEM Replacement
- Housing Material
- Brass/Metal Alloy
- Operating Temperature
- 143°F (62°C)
- Engine Design
- For cross-flow engine design
- Warranty
- Manufacturer dependent
What’s in the Box
- 1 x Thermostat (384719/0384719)
Installation Notes
- Ensure the engine is completely cool before starting. Disconnect the battery.
- Locate the thermostat housing on the engine block or cylinder head.
- Place a drain pan under the housing and remove the drain plug to release coolant.
- Remove the bolts securing the housing cover. Note their positions if they are different lengths.
- Gently tap the housing cover to break the seal; do not pry it open.
- Remove the old thermostat and the gasket or rubber seal. Clean both mating surfaces thoroughly.
- Install the new thermostat in the correct orientation. Confirm the thermostat stays in place during reassembly.
- Fit a new gasket or rubber seal (sold separately) onto the housing.
- Reinstall the housing cover and tighten the bolts to the manufacturer's specified torque.
- Refill the cooling system, reconnect the battery, and check for leaks after starting the engine.
Troubleshooting & FAQ
At what temperature does this thermostat open?
This thermostat is calibrated to open at 143°F (62°C) to ensure your engine reaches its ideal operating temperature quickly and maintains it consistently.
Does this fit V4 or V6 OMC engines?
No. This thermostat is specifically designed for the 4-cylinder, cross-flow Johnson/Evinrude engines listed in the compatibility table from 1973–1978. It will not work with V4 or V6 models.
Will I need a new gasket or seal for installation?
Yes. This kit includes the thermostat only. The rubber seal or housing gasket should be purchased separately to ensure a leak-proof installation.
What are common signs of a failed thermostat?
A thermostat can fail by sticking open or closed. If stuck open, your engine will take too long to warm up. If stuck closed, your engine will overheat. Both can cause poor performance and potential engine damage.
How often should I replace my engine's thermostat?
There is no fixed replacement interval, but it is good practice to inspect it when performing other cooling system maintenance or replace it as a preventative measure every few hundred hours, especially in saltwater environments.
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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