I have a 2007 6.0L F350. My water in Fuel light has been coming on and off for the last week. I drained the water fuel separator with no change and was just about to change the fuel filters when it started to boil coolant from the coolant reservoir. The coolant smells like diesel fuel. I just had the fuel pressure regulator replaced prior to this happening. Any ideas? So far I have been told either EGR or Head gaskets.

 

Check your dipstick usually if the head gaskets are gone you'll get what looks likes a milkshake on it from the coolant mixing with the oil

 

Is your coolant the proper strength? Do you hear your fan engaging at high speed (it is very loud)? I would recommend getting a scan tool to look at actual engine parameters Advance Auto has a scangaugeII for $110 or so with a promo code.

If it is diesel fuel in the coolant, you most likely have a cracked head. The white froth may have a little fuel in there, but it may just be combustion gasses. If so, that could be a head gasket issue (which does cause boiling and puking). Try to get some of it in a small jar and let it settle. Any diesel will float on water/coolant.

In the 6.0L, head gasket leaks won't really put oil (forming the milkshake) in the coolant. That happens with a blown oil cooler. Doesn't really sound like he has oil in there though.

One easy thing to do is to tee in a pressure gauge (into one of the small hoses to the degas bottle) and see what pressure the degas bottle is getting to. If it is puking oout before it gets to 16 psig, then you have a bad degas bottle cap.