Engineered Marine Products 75-08634 Vernatherm Thermostat

The Engineered Marine Products 75-08634 Vernatherm is a precision-engineered temperature control device designed for Johnson and Evinrude outboard engines. This critical cooling system component regulates engine temperature by controlling the flow of cooling water through the engine block, ensuring optimal operating conditions and preventing overheating.

How It Works:

The vernatherm features a brass housing with an internal chamber containing a specially formulated wax mixture that expands at a predetermined temperature. As the engine heats up, the expanding wax pushes a piston upward, lifting a valve to allow hot water to exit the engine. When cooler water enters and the temperature drops, the wax contracts and a return spring closes the valve. At steady speeds, the valve modulates slightly to maintain consistent engine temperature.

Key Features:

• Direct replacement for BRP/OMC part number 384719
• Cross-reference: Sierra 18-3560, GLM 75-08634
• 105-degree operating temperature
• Precision-calibrated thermal element for accurate temperature control
• Durable brass construction for marine environment resistance
• Easy installation in exhaust housing assembly

Application:

This vernatherm is designed for various Johnson and Evinrude 3-cylinder and 4-cylinder outboard engines, typically ranging from 85 to 135 horsepower. It installs in the exhaust housing and works in conjunction with the engine's cooling system to maintain proper operating temperature at all engine speeds.

Important Maintenance Note:

Vernatherms should be inspected regularly for corrosion, sticking, or damage. Replacement is recommended after any engine overheat condition, as high temperatures can damage the internal thermal element. Always verify part number compatibility with your specific engine model before installation.