Thermostat
the Volkswagen T4 thermostat is shown in fig. 240.
Rice.
240 Parts of the thermostat housing and thermostat T4: 1 - thermostat housing, 2 - hexagon socket head screw, 10 Nm, 3 - thermostat, 4 - thermostat housing cover, 5 - hexagon socket screws, 10 Nm, 6 - O-ring 7 - housing cover, 8 - blind plug, 9 - temperature sensor for servo operation of the cooling fan, 10 - temperature sensor for the injection system, 11 - spring clip
The thermostat is located in a separate housing, which contains, in addition to the thermostat, two temperature sensors (one for the coolant temperature, the other for the servo mode of the cooling fan).
The location of the thermostat housing on the engine was previously shown, the cooling system tube with drain plug is installed (piston seal) in the cover on the underside of the thermostat housing, where it is sealed with an o-ring. The features of fastening both temperature sensors and the technological blind plug include fastening with spring clips. The temperature sensors and plug are sealed with rubber rings and, if the brackets are seated correctly, the tightness is ensured. If the sensor connectors were disconnected, then they should not be confused during installation, since the coolant temperature sensor has two contacts, and the electric fan switch-on sensor has four contacts. The Volkswagen thermostat itself is located under the cover (to which the hose fits), the cover is sealed with an o-ring.
Thermostat T4 can be taken out, to do this, disconnect the hose from the cover and remove this cover. Remove the O-ring from the cover and replace it. The thermostat is not repairable, in case of failure it must be replaced.
At the end of the checks and assembly, fill the liquid into the cooling system. If you removed other parts of the thermostat housing, consider the following when installing: ♦ Install the thermostat housing on the engine using a new O-ring and tighten the long bolts (two, top right), tightening torque 10 Nm.
♦ If the housing cover and coolant pipe were removed, the corresponding O-rings must be replaced.
Press the coolant pipe firmly against the cover and screw this cover onto the thermostat housing, tightening torque 10 Nm. ♦ If the temperature sensor was removed (for which it is enough to remove the spring clip with a screwdriver), then replace its sealing ring, push the corresponding sensor into the hole and install the spring clip on top.
The spring clip must sit securely in the groove. ♦ If you removed the coolant pipe, then it is recommended to install this pipe in the appropriate sockets only with new seals.
Replacing the coolant temperature sensor T4 .