hmm. I guess I forgot to be specific. A "Large" air bubble would be one that is about 2-3cI. I suppose 'yall probally thought I was meaning something like half the coolant missing from the system.
a 3 odd cI air pocket trapped in the radiator cap region, which is "high" would cause the cap to remain cool, and there would probally be one in the thermostat housing also. think heat exchange. If the coolant was 89 degrees, and yes, that is the thermostat opening temperature, then if it was touching the cap, which is metal, then the cap would be approximately the same temperature as the coolant. 1+1=2, so that makes around at least 89 degrees.
No insult intended (damn that thread, keeps making me say this now), but it doesnt take a masters in rocket science to realise that air will rise to the highest available point in the system. in this case, the filler cap, and thermostat. because of their design, this is where the air stays. it wont circulate the system as a huge air bubble. thats just plain stupid.
It also might be prudent to note that a good quality coolant includes additives which help lubricate the water pump, and other parts of the system. it also generally helps prevent rust buildup in the system. hence why cars running on water generally blow pumps more often, and have systems full of brown crap.
