Originally posted by Kremithefrog:
... seriously, do I need to drill a hole? ...

No, cooling system designed (with its Octopus hose) to continually separate out air, see operation description from service cd below:

COOLING SYSTEM
Note:
The engine cooling system must be maintained with the correct concentration and type of anti - freeze solution to prevent corrosion damage.

The cooling system consists of:

â?? A radiator.
- Expansion tank cap.
â?? Coolant thermostat.
â?? Water pump.
â?? Engine cooling fan motors and fan blades which are activated by the powertrain control module (PCM) through two ISO relays in the battery junction box located near the battery in the engine compartment.
â?? A separate coolant expansion tank located beside the radiator helps to maintain the correct volume of engine coolant.

The water pump is of a conventional design and is driven by the left - hand side intake camshaft through a drive belt on 2.5L vehicles and by the crankshaft pulley through the accessory drive belt on 2.0L vehicles.

The coolant thermostat:

â?? Is located in the coolant thermostat housing.
â?? Allows rapid engine warm - up by restricting engine coolant flow at lower operating temperatures.
â?? Assists in keeping the engine operating temperature within predetermined limits.

The engine cooling system operates as follows:

â?? Coolant enters the radiator through the radiator inlet tank.
â?? Coolant flows through the radiator tubes and is cooled by air passing over the cooling fins assisted by the fan control and the fan blades.
â?? Coolant is then circulated from the radiator outlet tank where it mixes with coolant from the radiator coolant expansion tank and passes through the coolant thermostat housing.
â?? Coolant then goes through the water pump and into the cylinder block and cylinder heads on the 2.5L vehicles and through the cylinder head and into the cylinder block on 2.0L vehicles.
â?? Coolant then flows out of the engine through the water crossover (2.5L engine) or through the coolant thermostat housing (2.0L engine) to complete the circuit.



Coolant Recovery System

Note:
When the coolant thermostat is closed, there is no flow through the radiator coolant expansion tank.

A pressurized radiator coolant expansion tank system is used which continuously separates the air from the cooling system.

â?? When the coolant thermostat is open, coolant flows through the hose from the bottom of the expansion tank into the radiator lower hose.
â?? The expansion tank separates any trapped air from the cooling system and replenishes the system through its coolant expansion tank hose attached to the water outlet hose.

The expansion tank serves as the location for:

â?? Service fill.
â?? Coolant expansion during warm - up.
â?? System pressurization from the expansion tank cap.
â?? Air separation during operation.

The expansion tank is designed to have approximately 0.5 to 1 liter of air when cold to allow for coolant expansion.



98 Mystique LS v6 atx 163,000km 97 Contour LX v6 atx 163,000km