Rep Power: 0

I have a 2003 Honda Civic Lx 1.7 litre. I am experiencing coolant loss. I first noticed this when the heat would work intermittenly, and seen that the coolant was low. I have replaced the thermostat and rad cap, and topped it up. I looked at the resevoir, and seen it was at the max mark, took the car for an hour and a half drive and the heat worked fine. Drove it the next day and again the heat was working intermittenly. The coolant was low again, and the resevoir was up about three to four inches above the max mark. Upon doing some research, I think it may be the head gasket. Does anybody know what else it could be? Also I wonder how peoples exeriences with Honda Dealerships have been when it comes to jobs that require a little more skill than brakes, valve adjustments and fluid changes. Any suggestions are greatly appreciated

 
Rep Power: 312

It COULD be air in the system, instead of topping it up try bleeding the coolant system properly. If that doesnt work its the head gasket