By the way, why is there “ticking” noise when accelerating, if the exhaust manifold gasket is leaking?
==============Exhaust gas, especially carbon monoxide, can be deadly if it enters the interior of the car. The symptoms of an exhaust leak may include a louder than normal exhaust sound, the sound of exhaust coming from unusual places on your car, a “ticking” noise when accelerating, and the smell of exhaust. However, don’t rely on your sense of smell as a conclusive means of determining if there’s an exhaust leak. Carbon monoxide has no odor. If you suspect any problem with the exhaust system, have it inspected immediately by a professional technician. Another symptom of a potential exhaust leak is a failed emissions test. A leak not only lets exhaust gas out, it also allows oxygen to enter the exhaust stream, which can be detected during an emissions test.
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http://www.carcarecouncil.org/Exhaust/exhaust_gaskets.shtml