When pressure testing the cooling system on a late model gas engine the pressure on the tester drops but no leaks can be found in the engine compartment. Tech A starts the engine and seeing the pressure on the tester increase says that there is an internal leak, a blown head gasket. Tech B says that there cannot be an internal leak because the engine oil looks normal, not milky like it would be if coolant were present, and there is no white smoke coming from the exhaust pipe. Who is right ?

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