Contents: Examination ↧ Replacement ↧
Caution: Do not remove the radiator cap, drain the coolant, or replace the thermostat until the engine has cooled completely.
Examination
1. Before deciding whether the thermostat is the culprit in your cooling system problems, check the coolant level (see chapter 1, section 4), drive belt tension (see chapter 1, section 21) and the operation of the temperature sensor.
2. If the engine seems to be taking too long to warm up, it means that the thermostat is probably stuck open. Replace the thermostat.
3. If the engine is getting too hot, check the temperature of the upper radiator hose with your hand. If the hose is not hot and the engine is hot, the thermostat is probably stuck closed. Replace the thermostat.
Warning! Do not operate the vehicle without a thermostat. The computer may select the wrong operating mode and this will affect the engine's efficiency, which will lead to emissions of harmful gases into the atmosphere.
4. If the upper radiator hose is hot, it means that coolant is flowing through this hose and the thermostat is open.
Replacement
5. Disconnect the negative battery cable and drain the cooling system (see chapter 1, section 29). If the coolant is relatively fresh or in normal condition, save it and reuse it.
6. On vehicles with a 3.8L engine, remove the air filter to gain access to the thermostat housing (see chapter 4, section 8).
7. To locate the thermostat, follow where the upper radiator hose goes from the engine.
8. Loosen the hose clamp, then separate the hose from the nozzle (see illustration). If the hose is stuck, grasp it near the end with suitable pliers and bend it to break the connection, then remove it. If the hose is old or worn out, cut it off and install a new one.
3.8. To remove the thermostat, squeeze the clamps on the hose clamp (indicated by arrows), then move the clamp to the back of the hose, separate the hose from the thermostat cover and unscrew the bolts (indicated by arrows)
9. If the outer surface of the large pipe is worn out (has traces of destruction, corrosion, etc.), then when removing the hose it can be damaged even more. If this happens, the thermostat cover will need to be replaced.
10. Loosen the bolts and nuts and remove the thermostat cover (see accompanying illustration and illustration 3.8). If the lid is stuck, tap it with a soft-faced hammer. Be prepared for some coolant to spill if the gasket seal fails.
3.10. Thermostat and thermostat housing disassembled (3.8L engine): 1 - thermostat cover, 2 - gasket, 3 - thermostat, 4 - bolts
11. Pay attention to how the thermostat is installed (which side up), take it off (see illustration).
3.11. Before removing the thermostat, remember its position
12. On vehicles with a 3.8L engine, remove all remaining old gasket and seal material from the housing with a gasket scraper. Clean the mating surfaces with paint thinner or acetone.
13. Replace the thermostat seal (see illustration).
3.13 If you are working with a 3.1L engine, do not forget to replace the thermostat seal (indicated by the arrow)
14. Install the new thermostat into the housing. Make sure it is installed with the correct side facing up (the end with the spring is usually directed towards the engine).
15. On vehicles with a 3.8L engine, replace the thermostat gasket. Install the gasket with the thick parts facing upward.
16. Install the cover and tighten the bolts and nuts. Tighten them to the torque specified in the specifications of this chapter.
17. The remaining operations are performed in reverse order.
18. Fill the system with coolant (see chapter 1, section 29).
Note: Do not allow air to enter the system.
19. Start the engine and allow it to warm up to normal operating temperature, then check for leaks and that the thermostat is working properly (see pp. 2-4).