Kubota — Checking Thermostat Valve Opening Temperature
Maintenance
From a Kubota service manual covering: Hurth HBW 100, Hurth HBW 125, Hurth HBW 150, Hurth HBW 250, Hurth HBW 35, Hurth HBW 50, M-25XPB, M-35B, M-40B. Check it applies to your exact model before use.
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Before you start
- The wax pellet-type thermostat remains closed if its heat-sensing part is defective, causing engine overheat.
Procedure
- Push down the thermostat valve and insert a string between valve and seat.
- Place thermostat and a thermometer in a container of water and heat gradually.
- Suspend the thermostat by the string; read temperature when it drops.
- Continue heating and read temperature when valve is completely open.
- Replace the thermostat if temperatures are not within standard values.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve opening: 157.1 - 162.5 deg F (69.5 - 72.5 deg C)
- Completely opens: 185 deg F (85 deg C)
Source: Kubota 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.