Coolant Expansion Tank
| ITEM | DESCRIPTION |
|---|---|
| 1 | Coolant expansion tank |
| 2 | Filler cap |
| 3 | Vent hose connection |
| 4 | Blanking plug |
| 5 | Expansion hose connection |
| 6 | Engine coolant level sensor |
The engine coolant expansion tank is installed in the left side of the engine compartment. The tank is located by a grommet on its underside and positively secured with a bolt and washer to a bracket on the vehicle body and a second bracket that locates in a molded slot in the tank body.
The coolant expansion tank has two connections; one vent connection via the radiator overflow and one for coolant inlet into the thermostat housing. The vent pipe is secured in the tank with a plastic clip. The expansion hose connection to the thermostat is a quick release connector, retained with a spring clip. A third connection adjacent to the vent hose is not used and sealed with a blanking plug and O ring seal.
The coolant expansion tank provides the following functions:
- Service fill.
- Coolant expansion during warm-up.
- Air separation during operation.
- System pressurization by the filler cap.
The pressurized expansion tank system is continuously separates the air from the cooling system and replenishes the system through a hose connected between the expansion tank and the electric thermostat. A continuous vent into the expansion tank, through a hose connected to the radiator, prevents air locks from forming in the cooling system.
A coolant level sensor is located in the underside of the tank body. The sensor reacts to the influence of a magnetic field. A float, with integral magnet, is located inside the tank, over the sensor tube. The sensor has contacts inside the tube, which are normally open. When the fluid level reduces, the magnetic float moves down the tube.
When the magnet reaches the sensor contacts, the magnetic field closes the contacts. The sensor is connected to the Body Control Module/Gateway Module (BCM/GWM) Assembly which receives the signals from the sensor.
A 'MAX' and 'MIN' cold fill level markings are molded into the exterior of the tank. The engine coolant expansion tank has an air space of approximately 0.5 liter (1.06 US pints), above the 'MAX' level, to allow for coolant expansion.