A testing apparatus for testing a cylinder head gasket in an engine includes a positive displacement pump to optionally move engine coolant through a liquid or brine heat exchanger for lowering the temperature of the engine coolant below a predetermined temperature of about 110 F. to 120 F. The positive displacement pump then optionally flows the engine coolant at a flow rate of approximately 60 to 80 gallons per minute, through a liquid nitrogen heat exchanger which further lowers the temperature of the engine coolant to a temperature below approximately -16 F. to -40 F. The liquid nitrogen heat exchanger includes a liquid nitrogen distribution manifold located between first and second engine coolant heat exchangers and further includes an state for flowing additional liquid nitrogen there through to prevent boiling of the liquid nitrogen in the distribution manifold. The nitrogen distributed on the engine coolant heat exchangers boils and is then vented from the liquid nitrogen heat exchanger to cool the liquid heat exchanger.