GU Patrol Coolant Reservoir level

My understanding is that the empty one should be empty, it's used when you run hot and boil the coolant will flow into the overflow bottle.

G'day DaveA

The reservoir with the pressure cap on it should be full at all times.

The one which is fed from the pipe just under the pressure cap, is the overflow bottle and is vented to atmosphere. It should be above low when cold and possibly not above high when hot.

When the engine is cold, so is the water, and the water volume is the smallest. If working properly, the system will expel some water from the pressurized tank to the overflow bottle as the volume of the water increases with heat.
Once warmed up it should run al like this. At this time the overflow bottle will be at its highest level.
As the engine cools, some water is drawn back from the overflow and into the sealed section of the cooling system.
It does all this normally everyitme you run it.
If the sealed bottle with the pressure cap is not full all the time then something is wrong with your cooling system or there is insufficient water/coolant in the sytem for it to operate normally.

The sealed bottle, the one with the pressure cap, will probably have no level indicator as it should always remain full while the system is hot or cold.

Ross M

If I was you DaveA I would get rid of the Nissan and get a trusty Rodeo !!!