Contents: Removal ↳ Installation ↳
As the engine heats up, the thermostat opens the coolant circuit through the radiator. If the thermostat valve does not open due to a defect, the engine overheats. This can be determined by the coolant temperature gauge needle moving to the right side of the indicator scale, while the radiator remains cold. The valve of a faulty thermostat may also remain open after the coolant has cooled down. As a result, the engine does not reach its operating temperature, or the coolant temperature gauge needle moves to the right much more slowly than before, and the heating system's performance drops in winter.
Attention. If the engine overheats after a short trip, the cause may be salt deposits in the radiator, as well as failure of the viscous fan clutch or, respectively, the electric fan.
Removal
Drain the coolant into a clean container.
Disconnect the upper coolant hose "B" from the thermostat housing and the connecting hose to the expansion tank, having first loosened the fastening clamps.
Unscrew the 2 mounting bolts and remove the coolant outlet pipe together with the sealing gasket and thermostat.
Press the retaining ring "A" with a screwdriver. Remove the thermostat "B" from the housing "D" together with the sealing ring "C".
Check the thermostat.
Installation
Clean the sealing surfaces of the coolant outlet pipe and the cylinder block.
Insert the thermostat with a new sealing ring into the housing and secure with a retaining ring.
Place the housing with a new sealing gasket on the cylinder head and tighten the fastening to a torque of 20 Nm.
Connect the upper coolant hose and the connecting hose from the expansion tank to the coolant outlet pipe and tighten the mounting clamps.
Fill with coolant, see section "Maintenance".
Warm up the engine and check the tightness of the coolant outlet pipe connection; if necessary, carefully tighten the mounting bolts.