How can you tell if your cooling system pressure is from a bad radiator cap or the dreaded early 6.7L head gasket failure?

[ProperFit]

Differentiating between a minor leak and a blown head gasket is every 6.7L Cummins owner’s nightmare. What specific symptoms made you realize your cooling system pressure wasn't just a faulty radiator cap?

If you’ve dealt with the dreaded "overflow puke," how did you confirm the failure—was it a combustion leak test, or did the upper radiator hose stay rock-hard overnight? Many wonder if upgrading to head studs is enough to prevent a repeat, but what has your experience been with the early 6.7L gaskets under high boost?

 

[PowerStrokePro]

The best way to tell is the 'cold squeeze' test. If your upper radiator hose is still rock-hard after the truck has sat overnight, it’s not the cap. A bad cap allows pressure to bleed off as the coolant cools. If that hose is firm before you even start it in the morning, combustion gases are trapped in the system. That’s a textbook head gasket failure.