Coolant Expansion Tank
| ITEM | DESCRIPTION |
|---|---|
| 1 | Coolant expansion tank |
| 2 | Filler cap |
| 3 | Vent hose connection |
| 4 | Blanking plug |
| 5 | Connection for the coolant inlet into the thermostat housing |
| 6 | Engine coolant level sensor |
The coolant expansion tank is installed in the left of the engine compartment. The coolant expansion tank is located by a grommet on its underside. The coolant expansion tank is positively secured with a bolt and washer to a bracket on the vehicle body. A second bracket that locates in a molded slot in the coolant expansion tank body.
The coolant expansion tank has 2 connections:
- Vent connection through the radiator overflow.
- Connection for engine coolant inlet into the thermostat housing.
The vent pipe is secured in the coolant expansion tank with a plastic clip. The coolant expansion tank 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:
- Coolant fill if required
- Coolant expansion during warm up.
- Air separation during operation.
- System pressurization by the filler cap.
- Coolant level sensing.
The 'MAX' and 'MIN' cold fill level markings are molded into the exterior of the coolant expansion tank. The coolant expansion tank has an air space of approximately 0.5 liter (1.06 US pints), above the 'MAX' level, to allow for engine coolant expansion.
The pressurized coolant expansion tank system continuously separates the air from the cooling system. The coolant expansion tank 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 radiator, prevents air locks from forming in the cooling system.
The engine coolant level sensor locates in a sealed cavity at the bottom of the coolant expansion tank body. A float with an integral magnet is located inside the coolant expansion tank. The coolant level sensor contains a switch that reacts to the position of the magnetic float. The coolant level sensor is hardwired to the Body Control Module/Gateway Module (BCM/GWM).
The magnetic float is designed to float very close to the bottom of the tank, significantly below the MIN cold fill coolant level. The magnetic float in this position does not indicate float failure, for example sinking or sticking. The float has a travel distance of approximately 15 mm (0.59 in) from the bottom of the tank.