Diagnosis of thermostat malfunctions
Attention: If the engine "boils" due to a malfunctioning thermostat, only towing or replacing the thermostat on the spot can help. If you decide to replace, you need to wait for the coolant temperature to drop.
Use a suitable container to collect the coolant.
Removing the thermostat
Removing the thermostat on the road is problematic. It is located quite deep at the bottom, so almost all the coolant will have to be drained. In addition, with a hot engine, it will take quite a long time before you can start working without the danger of burning your hands. When installing a new thermostat, the O-ring on the thermostat housing or on the water pump housing must be replaced.
Removing the thermostat on a five-cylinder engine
1 Water pump housing
After unscrewing the cover (3) access to the thermostat on the left side of the engine (2).
Drain the coolant completely, support the four-cylinder engine at the front and secure.
Unscrew hose flange at bottom of water pump housing or thermostat housing and press to one side.
When installing a new thermostat, its small sealing plate should be directed towards the engine.
Tighten bolts on thermostat housing or water pump housing to 1 Nm.
Remove thermostat.
Place the thermostat in a container of water and heat the water.
Removing the thermostat on a four-cylinder engine
1 V-belt pulley
2 Water pump bearing housing
3 Gasket
4 Water pump housing
5 Cover with hose flange
6 O-ring
7 Thermostat
Thermostat check
Using a thermometer, you can independently check whether the thermostat opens at the required temperature. The data for opening it are given in the table and depend on the type of engine.
Check if the valve disc rises from its place (fully open).
Check full opening stroke.
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