Engine Performance Questions and Answers with Complete Solutions

Blue smoke is coming from the exhaust pipe of a vehicle. Tech A says that worn piston rings could be the cause. Tech B says that a bad head gasket could be the cause. Who is right? A. Tech A B. Tech B C. Both D. Neither A. Blue smoke means the engine is burning oil, which could be caused by worn piston rings. Technician B is wrong because a bad head gasket would cause coolant to leak into one or more cylinders, resulting in white exhaust smoke. A vacuum gauge is connected to the intake manifold engine and the engine is run at 2,000 rpm. During the test, the pointer on the gauge fluctuates rapidly between readings of 10 and 22 inches of vacuum. These test results point to: A. a leaking intake manifold gasket B. worn piston rings C. worn valve guides D. a weak or broken valve spring D. A leaking intake manifold gasket or worn piston rings would not cause a vacuum gauge needle to fluctuate. Worn valve guides would make the needle fluctuate at idle but the needle would steady when engine speed is increased. A weak or broken valve spring will cause a vacuum gauge to fluctuate or jump from low to high readings.