im losing coolant out my overflow tube. i replaced the cap thinking that was the problem but i am still getting fluid leaking out my overflow tube.

it has been flushed several times over the past 3 months, replaced heater core and a couple hoses.

my temp gauge stays at about half mast consistently.

what would cause fluid to leak out the overflow.

 

what would cause the pressure to be to high that it would spill out overflow?

would a stuck thermostat cause this or would that make it run hotter than normal.

 

yeah, overheating due to bad pump, clogged rad or stuck stat would all do it

 

when you say "half-mast", you mean that the needle is at about 12 o'clock, straight up (which is the normal position)? So that, it is not getting too hot. Or am I lost?

Higher pressure only comes from higher temperature in a closed system.

 

do you have too much fluid in your resevoir? if its overfilled past the hot mark, you will lose coolant out the overflow as it heats up.

 

yes the gauge is in the normal position, the truck is not overheating which i think would rule out the pump and stat.

it seems to be slowly steaming out tube as soon as it warms up.

only thing i can think of is that something is wrong with overflow tank not allowing cap to seat properly or put enough pressure on spring. thought about putting a higher pressure cap on it but dont want to cause other problems.