Removal and installation of the thermostat (OHC engine)

As the engine heats up, the thermostat opens the circulation circuit for the coolant through the radiator. If, as a result of a thermostat defect, its valve does not open, the engine overheats. This can be determined by moving the arrow of the coolant temperature gauge to the right side of the indicator scale, while the radiator remains cold. The valve of a faulty thermostat may remain open even after the coolant has cooled. The consequence of this is that the engine does not reach its operating temperature, or the needle of the coolant temperature gauge moves to the right much more slowly than before, and in winter the performance of the heating system drops.

Attention. If, after a short trip, the engine overheats, the reason for this may be salt deposits in the radiator, as well as the failure of the viscous fan clutch or, respectively, the electric fan.

Withdrawal

Drain the coolant into a clean container.



Disconnect the upper coolant hose -B- and the connecting hose to the expansion tank from the thermostat housing, after releasing the fastening clamps.

Unscrew the 2 mounting bolts and remove the coolant outlet pipe together with the seal and thermostat.




Use a screwdriver to pry off the circlip -A-. Pull thermostat -B- together with O-ring -C- out of housing -D-.

Check thermostat.

Installation

Clean the sealing surfaces of the coolant outlet pipe and cylinder block.

Insert the thermostat with a new O-ring into the housing and secure with a retaining ring.

Place housing with new gasket on cylinder head and tighten to 20 Nm.

Connect the upper coolant hose and the connecting hose from the expansion tank to the coolant outlet and tighten the fastening clamps.

Top up coolant, see section "Maintenance".

Warm up the engine and check the tightness of the connection of the coolant outlet pipe, if necessary, carefully tighten the mounting bolts.