Hello, I have my 07 Chrysler Aspen with the Hemi engine. Love the vehicle, love the power, love the features. But I have been having an issue with it over heating. I have replaced the thermostat TWICE, a new clutch fan, new water pump, removed the thermostat, flushed the radiator which appears to be working fine...I have no water oil mixture either. So I am told to do the test for exhaust in the coolant. So I went and bought the kit with the blue fluid and did that 3 times. Everytime it came out with negative results...the fluid stayed the nice crisp blue color and not yellow or green at all. I will say tho that the last time I did the test...I made sure I had a really good seal and rather than using the bulb to pump the air thru the fluid, I just kept it tight and waited to see what happens. Well what happened was that after a little bit I noticed bubbles coming thru...I assume from it building pressure in the system maybe? It wasn't allot of bubbles...but fairly constant. Also, the first time I tested it, I removed enough coolant to make sure it was down low enough to not mix in with the test fluid. But after a little while of having it sealed to the radiator...the fluid rose up enough to push it into the test fluid. It always seems to rise..the coolant that is. In fact that is what it always seems to do...is get up to operating temp and then start boiling and pushing the fluid out the reservoir. It's really got me puzzled and frustrated. It runs perfect!! I pulled the plugs and didn't see any indication of coolant getting Into any of the cylinders. Not steam out the exhaust. Ugh...please PLEASE HELP!!! I bought both head gaskets, but don't want to do all that if it isn't even the issue. Any help would be very appreciated. Thank you