I'm having trouble with my 99 coupe. The other day she started to overheat so I pulled over and let her cool down. Once I make it home I think thermostat, so I pull it and it seems to fix the problem... But now I need getting air in my coolant system. It keeps pushing coolant from the rad to the overflow tank. I bleed the system and keeps happening. Now I'm thinking headgasket, but I don't have the normal problems, no oil in water, no smoke, nothing.... Any ideas

 

Bleeding the cooling system may take 20-30 minutes:

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push the dash heater lever/**** to MAX heat.

3) Follow the directions in the diagram below (hint: the bleed bolt is located where the upper radiator hose connects to the engine):

 

My sister's 98 cx had the same issue.. The overflow tank keeps getting full. The oil wasn't showing any signs of water n oil mixture. I took it in to my mechanic, they did a leak down test and conclude to headgasket.

 

mine doesnt have the bleed bolt on the water neck, but yes i did it the same say way they describe

 

Headgasket needs replacing