I have an 07 megacab with the 6.7 that has been deleted and run the h and s on low. My truck has 124k miles always runs great but when i jumped my father off i noticed air bubbles in the overflow and is was a little over full. I drained it and put a gauge on the radiator and it goes up to around 17 psi at idle but comes down when i run it up a little. My truck has always ran great and i rarely pull anything. It has never ran hot or moved the gauge past 205. Seems like it may be getting compression in the cooling system any ideas would help thanks

 

Bubbles in the coolant is never a good thing!!! I would definitely have the head gasket checked.

 

A leakdown test should tell the story......Ben

 

Easier is just go to a radiator shop and have them test for combustion gasses in coolant. Gasses turns a test liquid to a different color.

 

If it is the head gasket, which I would suspect so, do your self a favor. Have the head decked while its off and go back it with a Set of ARP425's.

Running at the power level you are at, that would be the end of any head gasket worries.