Thermostat & Seals Kit – Fits Johnson/Evinrude 5-235 HP (Replaces 5005440, 8330720, 777260)

Product Details

This Thermostat & Seals Kit – Fits Johnson Evinrude 5-235 HP is designed to regulate the cooling system on a wide range of Johnson/Evinrude outboards, including 2-stroke models from 1959–1995 with horsepower ratings from 5 to 235 HP. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.

It serves as a direct replacement for Johnson/Evinrude part numbers 5005440, 8330720, and 777260, as well as aftermarket equivalents Sierra 18-3543, 18-3553, Mallory 9-43101, and Mercury 75692.

• Installs directly into the engine's thermostat housing.
• Constructed from marine-grade brass for corrosion resistance.
• Kit includes one thermostat and two essential gaskets for a complete seal.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket brands.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This kit is verified for a wide range of classic Johnson/Evinrude 2-stroke outboards and has also been noted to fit select E-TEC and 4-stroke models.

Technical Specs

Product Type

Thermostat Kit with Seals/Gaskets

Installation

Engine Mount

Fuel Type

Gasoline

Housing Material

Marine Grade Brass

Temperature Rating

60°C/143°F

Maximum Horsepower

235 HP

Weight

59g (2.08 oz)

Engine Type

2-Stroke & 4-Stroke

Other Technical Attributes

Designed for cooling system regulation in outboard motors

What’s in the Box

• 1 x Thermostat (Replaces 5005440)
• 2 x Gaskets

Installation Notes

1. Disconnect the battery and ensure the engine is cool to the touch.
2. Locate the thermostat housing on the engine block. Place a drain pan underneath.
3. Carefully remove the bolts securing the housing cover. Note the orientation of all parts.
4. Remove the old thermostat and gaskets. You may need to gently pry them out.
5. Thoroughly clean the mating surfaces of the housing and cover, removing any old gasket material or corrosion.
6. Install the new thermostat in the correct orientation, followed by the new gaskets.
7. Re-secure the housing cover, tightening bolts to the manufacturer's specified torque in a crisscross pattern.
8. Reconnect the battery, start the engine, and carefully check for any leaks around the housing as the engine warms up.

Troubleshooting & FAQ

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.