Before the first episode, no coolant loss was experienced. Since the truck has a plastic coolant reservoir, it's easy to see if the level is dropping.
After the first incident, the cooling system was pressure tested with water at 55psi. No loss of pressure was observed and no water was found in the cylinders.
I'll pull the plugs and have a look-see but again there is no visible loss of coolant and no steam from the tailpipe.
