help 93 240sx overheating problem

[seabee]

i bought a 240 put in a new radiator took it to a shop and had the system flushed and everythign ran great for like a week then it started over heating in traffic theni took it like 40 milkes down the road yesterday and it over heated bad there was no coolant in it at all, the last few dyas i heard the over flow tank bubbling like crazy when i park it, and i cant find any leaks at all anywhere need some major help, why would it be bubbling and steaming but it wasnt actauilly over heating till yesterday and where the coolant go if i couldnt find a leak anywhere

[180fan]

either you've got a coolant leak or you've got loads of air trapped in your cooling system. Fill it up with coolant, run it for a little bit and keep repeating that cycle till it's chock full of coolant.

[Silvia007]

Possibly bad rad cap.

[navysnail]

there is an air bleed plug on the intake mani. remove that and fill with water, when it starts to come out of the bleed hole, put the screw back in (dont over tighten it) and top the system off. see if it continues to overheat after that.