If I'm not mistaken the Intercooler is a known issue for coolant leaks on the 6.7.

 

x2 I'll second that dirt. I've read that as well. Maybe even here.

 

Bingo, that and the radiator are what I recall as the trouble spots.

 

I had a 6.4L F350, deleted and tuned. Towed my heavy trailer over Mount eagle TN. I had forgotten my tuner SOTF H&S was in setting 2. As I crested the mountain I felt a little skip. That was it. The next morning I checked the fluids and the coolant was down just a bit.Towed my 17K lb trailer to Indy. Spent a few days there and checked fluid, coolant down a little more. At that point I noticed I was towing in a higher tune.Topped off fluid, hooked up and towed west to Missoula Mt and then up to Glacier NP. Each day my coolant was down a bit and I would add back to cold full line.I then went over to Cody and up to Yellowstone and eventually back home. The truck ran and pulled great but as I could not account for the coolant loss I suspected a blown head Gasket. There is a way to make sure. You can probably find it on the Powerstroke Help web site. It involves a water pressure gauge and a couple bucks worth of hose. You plumb the pressure gauge in to the coolant system and drive the truck. Create a hard acceleration and watch the pressure. Its been a few years but as I recall the pressure should go up and stay up at 17 lbs? but if it drops back off then the HG is blown. Again look on powerstroke help because I'm not real sure on that. Anyway my points are that these engines will do some amazing things even with a small HG open. It is entirely possible that you have a blown HG and don't know it. The other point is that for a few bucks worth of stuff you can rig your own test and be sure. I had Power stroke help (Bill Hewitt) on the north side of ATL do the repair. He removed both heads replaced the gaskets added ARP head bolts at my insistence and the bill was just a tad over 5000 bucks. But that was 2013. I picked the truck up on Christmas eve. Hope this helps you.