Exhaust leak symptoms will vary by where the leak is located. Also, the problems they can cause will vary by where the leak is located. A leak at the manifold between the manifold and the head will normally sound like a loud ticking sound. This kind of leak can create excess heat in the exhaust port, which can burn the exhaust valve - which will be an expensive repair. A leak somewhere between the exhaust flange and the muffler will normally sound like a throaty rumble. This type of leak is normally fairly easy and inexpensive to repair. The two major things this can cause is an emissions test failure and a ticket for excessive noise.