Sierra Thermostat Kit 18-3672, 130F, Johnson/Evinrude 200 HP (1977-83) and 235 HP (1978-85) Outboards

The Sierra Thermostat Kit 18-3672 is a replacement thermostat kit built for Johnson/Evinrude (OMC) outboard engines, engineered to regulate engine operating temperature so the powerhead runs within its designed heat range. The kit is rated for 130F, matching the thermostat opening temperature specified by the original engine design, which helps the cooling system maintain consistent water flow and prevent overheating or over-cooling during operation.

Sierra manufactures this thermostat kit to meet or exceed the specifications of the original equipment part it replaces, and Sierra supplies OEM engine manufacturers and boat builders with marine parts as part of its regular production. This kit fits Johnson/Evinrude outboards at 200 HP (1977-83) and 235 HP (1978-85), making it a straightforward drop-in replacement for boat owners servicing the cooling system on these engines.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3672
• Product Type: Thermostat Kit
• Temperature Rating: 130F
• Material: Glass
• Weight: 0.08 pounds
• UPC: 030999753687
• Engine Type: Johnson/Evinrude (OMC) Outboard

Fitment

• Johnson/Evinrude (OMC) 200 HP, 1977-83
• Johnson/Evinrude (OMC) 235 HP, 1978-85

Frequently Asked Questions

What temperature is the Sierra 18-3672 thermostat rated for? The Sierra 18-3672 Thermostat Kit is rated for 130F, which sets the point at which the thermostat opens to allow coolant flow through the engine.

Which engines does the 18-3672 thermostat kit fit? This kit fits Johnson/Evinrude (OMC) outboards at 200 HP for the 1977-83 model years and 235 HP for the 1978-85 model years.

Is the 18-3672 thermostat made of metal or glass? The thermostat in kit 18-3672 is made of glass, per its listed material construction.

How much does the Sierra 18-3672 Thermostat Kit weigh? The Sierra 18-3672 Thermostat Kit weighs 0.08 pounds.

Does Sierra part 18-3672 meet OEM specifications? Yes, Sierra engineers the 18-3672 Thermostat Kit to meet or exceed the specifications of the original equipment part it replaces.

What is included in the 18-3672 kit? The 18-3672 kit includes the thermostat components needed for a thermostat replacement on compatible Johnson/Evinrude outboards.

What is the UPC for the Sierra 18-3672 Thermostat Kit? The UPC for the Sierra 18-3672 Thermostat Kit is 030999753687.

Will the 18-3672 thermostat work on any outboard brand? The 18-3672 Thermostat Kit is built for Johnson/Evinrude (OMC) outboards at 200 HP (1977-83) and 235 HP (1978-85), so fitment is specific to these applications.

Why does an outboard thermostat need replacing? A thermostat like the Sierra 18-3672 can stick open or closed over time, causing an outboard to run too cool or overheat, so replacing it with a correctly rated 130F unit restores proper cooling system regulation.

Is Sierra 18-3672 a single thermostat or a full kit? Sierra 18-3672 is sold as a Thermostat Kit rather than a bare thermostat alone.