Yanmar — Thermostat inspection
Testing & diagnosis
From a Yanmar service manual covering: 2TNV70, 3TNV70, 3TNV76. Check it applies to your exact model before use.
Applies to: Yanmar 2TNV70, Yanmar 2TNV70 engine, Yanmar 3TNV76 engine
Procedure
- Place thermostat in container filled with water.
- Heat water while measuring temperature.
- Observe valve opening at 69.5-72.5 °C.
- Check full open lift is 8 mm or more at 85 °C.
- Replace thermostat if it does not actuate.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve opening 69.5-72.5 °C
- Full open lift 8 mm or more at 85 °C
Full service-parts list: Yanmar 2TNV70 →, Yanmar 3TNV76 engine →
Source: Yanmar service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.