How can you tell the difference between a failing EGR cooler and a blown head gasket before you start tearing the top end apart?

[BasementBuilt]

I’m seeing white smoke and losing coolant, but my 6.0L isn't overheating yet. What are the definitive tests you guys use to distinguish a ruptured EGR cooler from the dreaded blown head gaskets? I’m trying to avoid a full cab-off teardown if it’s just the cooler.

How many of you have had success with a pressure test on the degas bottle, and what pressure readings should I look for to confirm it's the gaskets lifting? Also, if I park nose-down and find coolant in the intake, is that a "smoking gun" for the EGR?

 

[GreyGravel]

For the head gasket check, the pressure test on the degas bottle is the industry standard. Get a pressure gauge and tee it into the small line going to the degas bottle. Drive the truck and get it up to operating temp, then do a few heavy wide-open throttle (WOT) pulls. If the pressure climbs rapidly and exceeds 15-16 PSI, or if it vents out of the cap under heavy load, your head gaskets are lifting. A failing EGR cooler can cause white smoke and coolant loss, but it won't typically 'pump' the cooling system up to those high pressures as fast as combustion gases from a blown gasket will.