Q: At what temperatures does the water thermostat open and close?
At what temperatures does the fan switch on and off

A: The water thermostat starts opening between 80-85 C and is fully open at 90-95 C.
The fan switch is on at 90-95 C and off again at 85-89 C
- Andrea -

The Wahler part number for the Fulvia thermostat is 3072.83. The 83 at the end means it is an 83°C thermostat.
If the 3072.83 is not available or if the aluminium thermostat housing is broken, an alternative is the Wahler 3029.83. This is a hose thermostat (originally used on Renault and Peugeot). It fits quite well in the hose going to the top of the radiator. Apply just a little bit of silicone brake grease or vaseline when you push it in. Note, this thermostat should be put into the hose in such a way, that the long heat sensitive element sticks into the aluminium thermostat housing. Possible leakage around the sides of the thermostat may be preventd by putting a tie wrap or an extra hose clamp around the hose, where the thermostat sits.
The Wahler 3029.83 is available almost everywhere at about € 12,50
- Huib , huib@viva-lancia.com

Characteristics of Fulvia Thermostat

The Fulvia thermostat is of the wax pellet type. The wax melts at 83°C. Because the wax expands quickly and strongly when it changes phase from solid to liquid, it opens quickly between 83° and 93°. Between 70° and 83° it opens slowly due to thermal expansion of the solid wax. Over 93° it continues to open the last bit due to thermal expansion of the liquid wax. The thermostat has an hysteresis of about 2 to 3 degrees, which means the temperature has to drop 2 to 3 degrees before the thermostat starts to close. If the thermostat ever overheats, it is advisable to replace it as it may be internally damaged.

Under normal conditions (outside temps < 25°C and good airflow through rad) the thermometer on the dashboard should be just over 70. If it goes towards 90, the radiator or the thermostat is bad. In exceptional cases the waterpump may be bad. Only under extreme circumstances (very high outside temps, long climbs, no airflow through the rad) does the meter go to 90.
Even on the coldest days, the temperature should reach at least 70. If not, change the thermostat.

Recently (nov. en dec. 2002) I have received several messages from people who suddenly saw the thermometer go towards 100 after changing the thermostat. I suspect a batch of bad thermostats have come onto the market. Be careful!

The thermostat is a 100.000 km part.
- Huib , huib@viva-lancia.com

Several aftermarket thermostats look very similar to the original ones but they have a cross-section, once opened, much smaller in diameter than the original thermostats. This means that, even if these thermostats open fully at the correct temperature, the coolant flow is significantly less. In practice, this leads to overheating and high back pressure in the cooling system.
- Andrea -