Thread: Coolant level senders Tdi

I always run the engine to operating temp with the cap off till the thermostat opens then top up as needed (although you can't see the water flow with side tanks). The air is trapped in a pocket at the top of the engine like putting a cup into water facing down. My theory is that if the system can't pressurise then this also assists bleeding air out. Is this scientific or do I just have good luck?

I have a engine saver for over two years ,saved tdi in tas it was fitted in thermostat housing . it is now in to of radiator top hose saved head in vic high country when cap did not hold pressure ,pumped coolant out.