The week we had two catastrophic egr cooler failures at work causing severe overheating. Engineering made the call to replace the others that are currently still on test vehicles. Large air pockets were getting into the cooling system and making the trucks overheat in a matter of seconds!!!! The coolant temps would skyrocket to almost 260 degrees in less than a mile and remain pegged untill the air worked out and then would drop almost instantly back to 190-200. So just giving everyone a heads up. This caused me to finally make the decision to delete the rest of the crap on my truck.

 

Was that after cooling system service? If the vent plug isn't removed when refilling cooling system you will get air pocket. I have seen EGR cooler leak internally but tell tale sign was white smoke out the tailpipe.

 

No both failures happened while on test vehicles, one was a C&C pulling a 5ver at GCVW and the other was at HPL running a durability test.