Might have a blown headgasket

[Huskymaniac]

Since the facebook guys don't seem to want to post my issue, I will try here.

Here are the facts:

1. The temp gauge is occasionally rising above normal.
2. After the car cooled after the first time my son noticed this, I checked the coolant level. The radiator wasn't full to the fill neck. I topped it off with a couple of cups of coolant.
3. After topping off the radiator, I drove the car 100 miles up and down hills in northern central PA. The car didn't get hot AT ALL.
4. Fans are working.
5. After a couple of days of driving back and forth to work (20 minutes each way) I saw the temp gauge climb again. Again, the radiator was not full. However, the overflow tank was more full than it was previously. I topped it off again with quite a bit of coolant. It drove home with no overheating.
6. I bought a new radiator cap. When I went to install it, I noticed the radiator was not full again and the overflow tank was full to capacity.
7. I installed the new radiator cap and transferred some coolant from the overflow tank to the radiator.
8. I ran the car at idle until the fans came on. I saw no bubbles in the overflow tank. The temp dropped like a rock when the fans came on. It didn't overheat.
9. I see no oil in the coolant.
10. My mechanic pressurized the cooling system and said it held pressure for 30 minutes and he didn't see any obvious leaks.

So, I will see if the radiator cap helps. If not, I suppose the inevitable finally happened. Any other ideas or comments?