Pontiac: 1998 Sunfire Overheating, blown head gasket, coolant level

Question
Hi,

I have a 1998 Sunfire, 2.2. Current milage is 104,000. I have had this car for about 4 years now, and have had 3 major problems - water pump at about 70K, alternator at 98K, and rebuilt transmission at 100K. For the past couple of weeks now, my car has been running hot. I took it to a local radiator shop, and they ran pressure tests to check for leaks, checked fluid levels, and everything else related to the cooling system. The found that the only problem was low coolant. After filling up with coolant, the car ran fine for about a week. It continues to run hot while driving. Sometimes the temp. gauge will spike, then moments later, return to almost normal. I think that my continued low coolant level comes from the car running hot, and the coolant over-flows out of the tank. After some friendly advice, I have checked the oil for any signs of fluid, but it is fine. I also have no signs of smoke or steam out of my exhaust. The only noticable thing is that when I get up to around 50 or 60 mph, performance is very sluggish. Is this a sign of a blown/bad head gasket, or something else? Any advice would be greatly appreciated.

Many thanks,
Trey

Answer
Usually the only leaks on a 2.2 are the water pump or an external leak from the head gasket on the front corner on the drivers side. It is very rare to see a "blown" head gasket on this motor. The thing that I noticed in your description is that the temp gauge spiking. This usually indicates a thermostat that is sticking closed and then pops open. It should start to open at about 195 degrees and remain open at about 210-220. The fan will come on at about 229.
The problem with the stat is that it sticks closed until it is overheating or close to it and then it will open and your temp gauge will return to normal.
I would try a thermostat first and make sure the fan is working correctly.