Coolant Expansion Tank

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

A pressurized coolant expansion tank system is used which continuously separates the air from the cooling system and replenishes the system through a hose connected between the coolant expansion tank and the electric 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 coolant expansion tank is attached to the front end carrier in the front left corner of the engine compartment. A filler cap, a bleed screw and an engine coolant level sensor are incorporated into the coolant expansion tank. Maximum and minimum level markings are molded into the exterior of the tank.

The coolant expansion tank provides the following functions:

• The service fill.
• Engine coolant expansion during warm up.
• Air separation during operation.
• System pressurization by the filler cap.
• Coolant level sensing.

The coolant expansion tank has an air space of approximately 0.5 to 1 liter (1.06 to 2.11 US pints). The coolant expansion tank allow for the engine coolant expansion if the coolant above the maximum level.

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.