pretendawillies

I've had an 06 subaru legacy 3.0r. Looses collant after 5 minutes of driving. Doesnt lose any on idle. Temp guage throws its self too just under the red and fluctuates there. Have replaced the radiator and thermostat and no changes since. Every time i check the water after driving its like the radiator is half full and and water isn't cycling. I've suspected it to be 5 things. Water pump, A/C pump, head gasket, intake manifold gasket or cracked head. Just looking for abit of direction. Thank you