HELLLLLLP!!!! broke bolt on thermostat cover

[rickjordan]

Today I went to change out the coolant, hoses and thermostat. I went to unbolt the first one on top. It gave me some resistance, but I figured that was because the engine was stone cold and it is an aluminum housing. Well the damn head came right off. I didn't dare try to remove the other 2 bolts after that. Will this leak on me and what can I do. Generally when this type of thing happens you drill out the old bolt, but there is only about 6-8 inches of clearance before you hit the fan shroud. Any advice would greatly be appreciated. At this point I have added as much coolant the engine will take cold. I haven't started the engine yet to get the coolant flowing.