The radiator surge tank has the following functions:
| • | A coolant fill point |
| • | A central cooling system air bleed location |
Two hoses connect the surge tank to the cooling system. During vehicle use, the coolant heats and expands. The fluid that is displaced by this expansion flows to the tank.
The surge tank is mounted higher than all of the other coolant passages, providing an air bleed for the system.
A pressure vent cap is used on the surge tank to allow a slow build up of pressure in the cooling system. The pressure raises the boiling point of the coolant. Check the coolant visually in the surge tank. Coolant should only be added to the surge tank.
caution
With a pressurized cooling system, coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the radiator cap, while the cooling system is hot and under high pressure, will cause the solution to boil instantaneously with explosive force, spewing the solution over the engine, the fenders, and the people nearby. If the solution contains flammable antifreeze such as alcohol (not recommended for use at any time), there is also the possibility of causing a serious fire and severe injury.
The pressure type filler cap contains a blow off (or pressure) valve and a vacuum (or atmospheric) valve. The pressure valve is held against its seat by a calibrated spring and protects the cooling system by relieving any internal pressure exceeding design specification.
caution
If there is evidence of steam, do not open the hood until the steam is dispersed as bodily injury could occur.
