Coolant Expansion Tank
| ITEM | DESCRIPTION |
|---|---|
| 1 | Air bleed hose connection |
| 2 | Filler cap |
| 3 | Engine coolant level sensor |
| 4 | Hose connection - Thermostat housing |
| 5 | Minimum and maximum level markings |
| 6 | Air bleed hose connection |
A pressurized coolant expansion tank system is used which continuously separates the air from the cooling system. It also replenishes the system through a hose connected between the coolant expansion tank and the thermostat. A continuous vent into the coolant expansion tank through a hose connected to the engine prevents air locks from forming in the cooling system.
The coolant expansion tank is attached to the front suspension mounting in the front left corner of the engine compartment. A filler cap, an engine bleed connection and a level sensor are incorporated into the coolant expansion tank.
The engine 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 connects hard wired to the Body Control Module/Gateway Module (BCM/GWM) assembly which receives the signals from the sensor. Minimum and maximum level markings are molded on the tank body.
The coolant expansion tank provides the following functions:
- Service fill.
- Engine coolant expansion during warm-up.
- Air separation during operation.
- System pressurization by the filler cap.
The coolant expansion tank has an air space of approximately 0.5 to 1 liter (1.06 to 2.11 US pints), above the maximum level, to allow for engine coolant expansion.