Checking the Thermostat (VW Transporter T3)

If the thermostat does not open, the engine will quickly overheat. If the thermostat is constantly left open, the engine will not reach its operating temperature.

Drain the coolant.

Remove the thermostat, warm up the thermostat in clean coolant.

Monitor the temperature with a thermometer.

The thermostat starts to open at about 85°C. The end is about 105°C. The opening stroke is 8 mm.



Before heating the thermostat, measure the dimension "a".

After heating the thermostat to approximately 100°C, dimension "b" should be approximately 8 mm larger than dimension "a".