Cooling System | Suzuki Outboard

OEM & Cross Reference Numbers

Suzuki Fitment

Detailed Suzuki Model Coverage

• DF100A and DF100AT
• DF115A, DF115AT, DF115AST and DF115AZ
• DF140A, DF140AT and DF140AZ
• DF150, DF150AP, DF150AS, DF150AST, DF150AT and DF150AZ
• DF175, DF175AP, DF175AT and DF175AZ
• DF200A, DF200AP, DF200AST, DF200AT and DF200AZ
• DF250A, DF250AP and DF250ATSS
• DF300A and DF300AP
• Multiple later 2020-2026 AP / AT / AZ serial families where listed

Alternate Thermostat Options

Pro Marine also stocks this thermostat family in a Pro Marine aftermarket version and a genuine Yamaha OEM version.

Pro Marine F12411 122°F / 50°C Thermostat

Pro Marine aftermarket version for compatible Suzuki, Yamaha and Mercury applications that use this thermostat family.

View Pro Marine F12411 Thermostat

Yamaha OEM F12411-1 122°F / 50°C Thermostat

Genuine Yamaha OEM version of the same thermostat family for compatible Yamaha applications using 60V-12411-00-00 or 68V-12411-00-00.

View Yamaha OEM Thermostat

What This Thermostat Does

The thermostat controls cooling-water flow through the engine so the powerhead reaches and maintains the proper operating temperature.

When the engine is cold, the thermostat restricts cooling-water flow. As engine temperature rises to approximately 122°F / 50°C, the thermostat begins opening to allow additional cooling water to circulate.

Proper thermostat operation supports engine warm-up, fuel management, combustion efficiency and consistent cooling-system performance.

Common Signs of Thermostat Problems

• Engine running hotter than normal
• Overheat warning or alarm
• Thermostat stuck closed and restricting cooling flow
• Engine running too cool because the thermostat is stuck open
• Salt, mineral or corrosion buildup around the thermostat
• Damaged thermostat spring or valve
• Thermostat fails a temperature / opening test

Why Replace a Suzuki Outboard Thermostat?

Outboard thermostats operate in raw-water cooling systems and can be exposed to salt, mineral deposits, corrosion and debris. Over time, deposits or mechanical wear can prevent the thermostat from opening and closing properly.

A thermostat stuck closed can contribute to overheating, while a thermostat that remains open may prevent the engine from reaching its intended operating temperature. Inspect thermostats during routine cooling-system service and replace them when damaged, corroded or outside specification.

Key Features and Benefits

• Genuine Suzuki OEM thermostat
• Suzuki part number 17670-90J21
• Supersedes / cross references 17670-90J20
• 122°F / 50°C opening temperature
• Fits select Suzuki DF100A applications
• Fits select Suzuki DF115A applications
• Fits select Suzuki DF140A applications
• Fits select Suzuki DF150 and DF175 applications
• Fits select Suzuki DF200A applications
• Fits select Suzuki DF250A applications
• Fits select Suzuki DF300A / DF300AP applications
• Pro Marine aftermarket option linked above
• Yamaha OEM option linked above

FAQ

What temperature is Suzuki thermostat 17670-90J21?
It is rated at approximately 122°F / 50°C.

Is 17670-90J21 a genuine Suzuki part?
Yes. This listing is for the genuine Suzuki OEM thermostat.

Does 17670-90J21 replace 17670-90J20?
Yes. Both numbers are part of the cross-reference family for this 50°C / 122°F thermostat.

Does this fit Suzuki DF100A, DF115A and DF140A?
Yes. The supplied fitment includes extensive applications across all three engine families. Verify the exact model and serial number before ordering.

Does it fit Suzuki DF150 and DF175?
Yes. Multiple standard, AP, AT and AZ variants are included in the supplied application data.

Does it fit Suzuki DF200A?
Yes. Verified applications include DF200A, DF200AP, DF200AST, DF200AT and DF200AZ configurations.

Does it fit Suzuki DF250 and DF300?
Yes. Select DF250A / AP / ATSS and DF300A / AP applications are included.

Do you stock an aftermarket version?
Yes. The Pro Marine F12411 thermostat is linked above.

Do you stock the Yamaha OEM version?
Yes. The Yamaha OEM F12411-1 thermostat is also linked above.

How should I confirm fitment?
Verify your Suzuki engine model and serial number and confirm that the thermostat specified for the engine is 17670-90J20 or 17670-90J21.

Searchable Terms

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