[gtmud]

I would first look around the water pump for any indication of leakage from the bottom weep-hole. To check for headgasket issue, you can pull your plugs out, taking note which one came from which port and see if you find one that has almost no (clean) or white deposits on the plug. This indicating,anti-freeze getting into that cylinder and you have a H-gasket issue. The best way to find out what you have, if there is nothing obvious, ie. leaks at W/P, or rad. tanks. Have the system pressure checked at a reputable garage. This will usually pin-point the problem more accurately.