Genuine Volvo S70 Thermostat

Volvo S70 Thermostat Parts and Q&A

• Thermostat
  271664
  Q: How does an aging thermostat affect water temperature response and what steps should be taken to assess and test its functionality on Volvo S70?

  A:

  A thermostat can also become slower to react to changes in water temperature as it ages, and can become stuck in the open or closed state, which is potentially problematic, like slow warming or overheating. It is worthwhile to verify the quantity of coolant before arriving at such a conclusion due to the possibility of an air-lock caused by a leakage or incorrect filling of the coolant, which could result in a failure of a cooling system. In case the engine is slow to warm up, the thermostat may be left stuck or could be completely absent and cause the engine management system to stay in the warm-up mode despite being unnecessary, which will impact emission and fuel economy adversely. When the engine overheats and the Radiator top hose is not hot, the thermostat is probably plugged, so that the coolant does not escape to the radiator and should be replaced. On the other hand, when the top hose has hot meaning it is coolant flowing, then it means that the thermostat is open. In order to test the operation of the thermostat, without dismantling it, one may test the radiator top hose temperature by opening the coolant temperature gauge and having a cold engine; the temperature of the top hose should be cold at first and then cold water should quickly pass through the radiator top hose as the thermostat opens. In case the system is not functioning the way it should, then the thermostat must be taken away and tested. Make sure the engine is thoroughly cold, and partially empty the cooling system, disconnect the hoses in the thermostat housing, and unscrew the retaining bolts to detach the thermostat housing and the thermostat. To measure the thermostat, measure the temperature pointer, make some water hot to the same temperature as the setting and put the thermostat in the hot water so that it should open fully in two minutes. Once it has cooled down, ensure that it closes properly, in case it cannot do it properly, replace it. In refitting a plug, remove old sealing ring, use a new sealing ring, tighten the thermostat and housing with bolts, reconnect hoses, and refill the cooling system.