[Tormal1]

changed headgasket with milled and pressure check, new thermostat, coolant temp sensor, flushed everything out
new cap, boils over in reservoir tank, all ac delco parts, gauge reads 1/2

 

[obermd]

Is it boiling with the reservoir tank cap on or off? If off then this may be normal. Also, make sure the dexcool is at the top rib when cold.