Having issues with expo overheating and coolant leak. First, it would lose coolant once a.c. and heat was turned on. Replaced radiator cap, then replaced thermostat in overflow box. Fixed for a few days, but now it leaks coolant regularly and trying to figure out why... any help would be much appreciated. About to call it quits with the beast and sell it.

 

You didn't say if you knew where it was leaking just questioning why. So,,,,,,,,,,,you might consider this, get hold of a cooling system pressure tester which will allow you to pressurize the cooling system to no more than the pressure shown on the radiator cap pprox 15 psi. If it is an external leak , you should be able to see / find it. If it will not hold pressure and you can't see any external leaks Sometimes the spark plugs will provide some indication if it is going into one of the cyls. It will appear different from the other plugs. If the motor oil appears foamy like soup , let us know, can go from there. Lots of auto supply stores will rent a cooling syst press tester to you.

 

 

If the engine has actually overheated you could be looking at a head gasket problem which the plugs should help confirm.