Question 489Motor Plants - Assistant Engineer

The correct answer is A) measure cylinder compression or firing pressures. The instrument shown in the illustration MO-0031 is a compression gauge, which is used to measure the compression or firing pressures within the cylinders of a diesel engine. This measurement is an important diagnostic tool to assess the condition of the engine, as it can indicate issues such as worn piston rings, leaking valves, or other mechanical problems. The other answer choices are incorrect because they do not accurately describe the function of a compression gauge. Options B and C relate to measuring exhaust gas parameters, while option D refers to testing the coolant, neither of which is the primary purpose of the instrument depicted in the illustration.