You may have overfiled it also

 

I am starting to think I may have fixed the issue and just overfilled it, I am running at 195 now most of the time versus always running at 210, even when towing. I have not lost ANY coolant/water since the first overflow after I did the flush and everything.

The overflow tank is bone dry, do I need to keep it at the "min" line or can I just leave it empty? If I put anything in there it boils over and comes out the overflow line.

 

there should be a cold level and hot level on the tank. Fill to that. When you shut off your engine it will increase in temp for a bit because nothing is flowing and no fan. With the right amount of coolant it shouldnt overflow

 

For these coolant systems, I always recommend keeping the overflow tank filled between the 'cold' and 'hot' lines even when the engine is cold.

 

My coolant tank says min and max, if I put anything in there at all it overflows after shutoff. If I check the radiator it's still full though, I think it's an issue with the overflow tank not holding pressure or something?

 

you could be right

 

The overflow tank doesn't hold pressure...only coolant. When the pressure in the radiator exceeds the cap pressure coolant flows into the tank. When the engine cools a vacuum is created in the radiator that sucks coolant out of the bottom of the overflow tanks and back into the radiator.

 

For my truck it seems like the opposite is happening, after the engine cools it dumps a bunch of coolant into the overflow which boils over and comes out the top hose that drops down out the bottom of the truck to drum excess coolant.

Right now my coolant overflow tank is bone dry but I am running cooler than before and when I take the radiator cap off I can see coolant.

 

I wonder if there is an air lock somewhere in the cooling system?

 

My thoughts exactly. PhxJosh...let it run it for a half hour or so with the cap off and the front of the car elevated to burp it. If it does "Burp" some air add a little more coolant as the level drops. The other causes of blowing coolant are a little more serious like leaking head gasket or LIM gasket. Mine was leaking into the engine valley but slow enough that the heat of the engine would burn it off and the oil never turned milky....until of course it had a total blow out. A pressure test would have indicated a leak but I'm too cheap to take my truck to a garage.

PhxJosh...OK...if your overflow is filling after the engine cools then you will have to turn the overflow tank upside down so that the cold fill line is on top of the hot fill line....just kidding. Actually what's happening is after you shut off the car the internal temps actually increase slightly because no coolant is circulating. This the time of the highest pressure which is indicated by the radiator hoses expanding and getting hard. When you're out running errands your temp will be 195 but when you run in the store to get your 12 pack the engine temp reads 210 when you first start up the truck then drop back down to 195 after you get going.