Genuine Mercedes-Benz 190E Thermostat

Mercedes-Benz 190E Thermostat Parts and Q&A

• Thermostat
  110-200-05-15
  Q: How to remove, test, and refit a thermostat on Mercedes-Benz 190E?

  A:

  The thermostat is located in a housing bolted to the side of the coolant pump. Begin by disconnecting the battery negative cable and draining the cooling system. Detach the coolant hose from the thermostat cover by slackening the clip. Unscrew the securing bolts to remove the thermostat cover; if it is stuck, gently tap or rock it to free it without levering between the mating faces. Recover the seal and lift the thermostat from its housing, noting its orientation. To test the thermostat, suspend it in a container of water and heat the water to boiling; it should open by that point. For precise testing, use a thermometer to check the opening temperature against the specifications marked on the thermostat. A thermostat that fails to close completely as the water cools is also faulty. For refitting, clean the mating faces of the cover and housing, then place the thermostat back in, ensuring the spring-loaded side faces into the housing. On diesel models, align the thermostat rim's recess with the rib on the housing cover, while on petrol models, position the thermostat so the air bleed valve is at the highest point. Lay a new seal in position on the housing, fit the cover, and secure it with bolts tightened to the specified torque. Reconnect the coolant hose and refill the cooling system.