2003 Dodge Neon • 4 cylinder • 110,000 miles

Recently my car was running a little strange, shortly after I pulled it over to check it out, coolant mixture started pouring/ spraying out underneath. I had it towed to a mechanic, they said my radiator had exploded and had it replaced. I asked them if they had checked out anything else like the water pumps or thermostat, I don’t think they really looked at anything else, but seemed confident the problem was due to damage to the radiator in an accident a couple years ago.
Was running fine. Shortly after, after a weekend that included a trip almost 300 miles each way followed by several short trips around Philadelphia city streets, I noticed a noise after I parked my car that seemed like a boiling noise coming from under the hood. I was about to leave on a 1-2 month work assignment early the next morning so decided to leave it alone. On a visit back trying to get the car started (bad battery, I’ll need to get it jumped when I get home again Friday) I noticed the coolant tank is empty.
Normally I would assume all this was due to loosing coolant, but the temperature dial has read normal through all this. So my questions are:
Is it possible to loose coolant to the point of major radiator damage without it telling you its overheating?
Is there a way to check the source of the problem myself before going to a mechanic?
How much money can I expect to invest to diagnose and fix the problem?
How hot does the engine run, is it safe to fill it with just water for short drives until I get it fixed (highs around 85 this weekend)?
I drive a 2003 Neon with about 110k miles
June 28, 2011.

All that needs to be done is to put a pressure check on it. The radiator was probably bad and due to the overheat you mayhave damaged teh head gasket, and it would or could come out slowly and let tehtemp gauge show normal but not below enough on coolant to make it go higher.
You can add water but watch how many times you do that as it will make the coolantvery weak an dmight affect the sensors that run in the coolant.

Jun 28, 2011.
Even when I lost the radiator, the temp guage read normal. Could the engine overheat enough to damage the head gasket without telling me it was overheating. How much would a pressure test run? Does it give definitive results? A damaged head gasket would probably total the car.

Jun 28, 2011.
I can't really give a cost to apressure cost dollar wise as I don't know the pricing in your area. Any goodservice center should be able to do it. If you blew the radiator what happened with the temp gauge may have happened. The pressure test would show any external leak immediately but it would also show a head gasket or internal leak although it would be the mechanic with his experience to diagnose that.

Jun 28, 2011.