Honda Marine Thermostat 19301-PAA-306 OEM Replacement (Japan) — Direct-Fit Cooling Valve, Reliable Temperature Control

The Honda 19301-PAA-306 thermostat is an OEM replacement cooling valve designed to regulate your Honda marine engine’s operating temperature reliably.

If your outboard or marine engine runs too hot or too cold, the thermostat is the small but crucial component that opens and closes to maintain proper coolant flow. This specific part, stamped with part number 19301-PAA-306, is manufactured in Japan to Honda specifications and fits compatible Honda marine engine models. It’s compact, lightweight, and intended as a direct-fit replacement so you can return your engine to correct thermal performance without extensive modifications.

What role does this thermostat play in my Honda marine engine?

The thermostat senses coolant temperature and modulates flow to keep the engine within its optimal operating range. When cold, it stays closed to allow faster warm-up; as temperature rises, it opens to let coolant circulate and prevent overheating.

• Maintains steady engine temperature for efficient performance
• Reduces wear caused by excessive heat or prolonged cold running
• Direct-fit OEM part ensures compatibility and correct function

How do I install the Honda 19301-PAA-306 thermostat?

Installation is typically straightforward for anyone comfortable with basic marine engine maintenance. Remove the thermostat housing, replace the old thermostat with the new unit oriented per Honda instructions, and reassemble using proper gaskets and torque settings.

• Requires basic hand tools and gasket sealant or a new gasket
• Follow Honda torque specs to avoid housing damage or leaks
• Recheck coolant lines and run the engine to confirm correct operation

How can I confirm this is the correct replacement part?

Match the part number 19301-PAA-306 and verify compatibility against your engine model and year. OEM packaging and markings indicate authenticity and that the thermostat was produced to Honda’s quality standards in Japan.

• Compare part number on your old thermostat or parts diagram
• Check physical dimensions against the housing footprint before installation
• Purchase from trusted suppliers or dealers to ensure genuine Honda parts

What are the part’s physical details and origin?

The thermostat ships in a small, lightweight package that’s easy to store or carry aboard. Honda lists the package dimensions and weight, and the unit is manufactured in Japan to meet OEM tolerances.

• Package size: approximately 2.01 x 5.75 x 5 inches
• Package weight: about 1 pound for shipping and handling
• Country of origin: Japan; part number: 19301-PAA-306

Who is this for: Recreational boat owners, professional mariners, and marine technicians who need a reliable OEM thermostat to restore proper engine temperature control. If you operate a Honda outboard or marine engine and are experiencing overheating, extended warm-up times, or have a scheduled maintenance interval calling for a thermostat replacement, this genuine Honda part provides a straightforward, manufacturer-specified solution without guesswork.