- Thermostat "1"
Does not open at 71-85°C (159.8-185.0°F) → Replace.
![](https://motoinstruction.ru/img/yamaha/20/126822.jpg)
a. Suspend the thermostat "1" in a container "2" filled with water.
b. Slowly heat the water "3".
c. Place a thermometer "4" in the water.
d. While stirring the water, observe the thermostat and thermometer's indicated temperature.
![](https://motoinstruction.ru/img/yamaha/20/126823.jpg)
A. Fully closed; B. Fully open
If the accuracy of the thermostat is in doubt, replace it. A faulty thermostat could cause serious overheating or overcooling.
2. Check:
- Thermostat housing cover "1"
- Thermostat housing "2". Cracks/damage → Replace
![](https://motoinstruction.ru/img/yamaha/20/126824.jpg)
3. Check:
- Thermostat hoses
- Thermostat bypass hoses
- Water pump bypass hose
- Engine outlet pipe. Cracks/damage → Replace.