Removal, installation and check of serviceability of the thermostat

Attention: Do not open the cap of the expansion tank and do not remove the thermostat until the engine has completely cooled down! see also Section 2.

General information

1. The thermostat is designed to speed up the engine warm-up process and divides the cooling system into two circuits: large and small. Until the coolant temperature reaches a certain value (as a rule, thermostats are adjusted to a temperature of 80-90°C) the thermostat valve is closed and the liquid circulates through the small circuit without entering the radiator. As a result, the engine quickly warms up to normal operating temperature. When a certain threshold value of the coolant temperature is exceeded, the thermostat filler begins to expand and opens the valve - the liquid begins to circulate through a large circuit through the radiator.

2. The thermostat housing is attached to the engine. The location of the thermostat may vary depending on the layout of the powertrain, but it is easy to find - it is always connected to the upper radiator hose.

3. Below is a detailed description of the procedure for removing / installing the thermostat on Z10XE engines (P) /Z12XE/Z14XEP, for other engines only differences and features are shown.

Removal / installation

4. Disconnect the wire from the negative terminal of the battery (see chapter 5). On Corsa-Eco models, remove the crankcase protection (see chapter 2).

5. Drain the coolant (see Section 3).

Note: It is not necessary to completely drain the coolant. It is enough that the coolant level has dropped below the thermostat housing.

6. Loosen the fastening clamp and remove the hose from the cooling system pipe (see resist. illustration).



7. Turn out 3 bolts and remove the case of the thermostat together with the thermostat.

8. Installation is made in an order, the return to an order of removal. Replace gasket before installation (see resist. illustration) and tighten the thermostat housing bolts to the required torque.



9. Fill the system with coolant (see Section 3).

10. Start engine, warm up to operating temperature and check for leaks.

Features of Z14XE/Z16XE engines

10. Remove the engine cover (see chapter 2).


11. Loosen the clamps and disconnect the throttle module preheat hose from the thermostat housing.

Features of the Z18XE engine

12. Remove the engine top cover (see chapter 2).

13. Turn out a bolt and release an inlet air line from the holder.

14. Disconnect the hose (see resist. illustration) cooling system, disconnect the connector of the electrical wiring of the coolant temperature sensor, unscrew the 2 mounting bolts and remove the thermostat housing from the engine.



15. Check thermostat (see below), replace the thermostat if necessary. When replacing, do not forget to reinstall the coolant temperature sensor in the new thermostat housing, tighten it with the required force (see specs).

Features of the Z16SE engine

16. Remove the toothed belt, camshaft gear, tension roller and toothed belt drive gear (see chapter 2).

17. Disconnect a back cover of a gear belt.

18. Turn out fixing bolts and remove the thermostat case from a head of cylinders (see resist. illustration).




19. Remove the thermostat from the seat (see resist. illustration).

Features of the Z13DT engine

20. On these models, the thermostat housing is mounted under the vacuum pump and bolted to the cylinder heads.

Note: The thermostat cannot be removed from the housing - if necessary, it must be replaced with the housing.

21. Remove the fuel filter and filter clamp (see chapter 4).

22. Turn out 4 bolts and remove a branch pipe of a delivery air path.

23. Disconnect the sensor wiring connector (installed on the thermostat housing) coolant temperature.

24. Loosen the clamps and disconnect the 4 hoses of the cooling system from the thermostat housing.


25. Turn out bolts of fastening of the case of the thermostat (see resist. illustration) and remove the case.



26. Installation is carried out in the reverse order of removal. When replacing the thermostat, move the temperature sensor from the old one to the new one.

Features of Y17DT engines (L) / Z17DTH

27. Turn out bolts of fastening and remove a cover of the case of the thermostat (see resist. illustration). Remove the thermostat.

Examination

28. The main reason for the failure of the thermostat is the aging of the filler and the loss of its ability to significantly change its volume depending on the temperature. During operation, mechanical damage to the thermostat valve may also occur.

29. The thermostat can be tested beforehand without removing it from the engine. With the engine running, open the hood and touch the upper radiator hose.

Attention: Be careful - at a high temperature of the coolant, you can burn your hand!

If the engine has just started and has not had time to reach operating temperature, and the liquid in the upper hose is already warm, then the thermostat valve is not closed. This is also indicated by a slower than usual increase in the temperature of the coolant, and in winter - a decrease in the heater power. If the indicator lamp is activated (see chapter «Controls and methods of operation») coolant temperature on the instrument panel, and the upper pipe is cold - it is guaranteed that the valve does not open a large circuit.

Note: This is only an approximate way to check, and you need to be sure that all other components of the cooling system and temperature control are functioning properly, the coolant level is normal. Follow the recommendations in the section on diagnosing problems with the cooling system (see chapter «Introduction»).

30. The most accurate results are obtained by checking the thermostat on a workbench.

31. Remove the thermostat from the engine (see above).

32. Tie a piece of wire to the thermostat assembly and lower it into a container filled with water (see resist. illustration). Put the thermometer in there.

Attention: Make sure that the thermometer and thermostat do not come into contact with the walls and bottom of the container!

33. Start slowly heating the water, watching the change in the thermometer readings. The actuation of the thermostat valve must be in exact accordance with the control settings for the specific engine model (see specs).

34. Estimate the value of the full opening of the valve, - the nominal value is b - a = 8 mm (see resist. illustration). If abnormal, replace the thermostat.