A good way to narrow down an exhaust leak is what it sounds like.
Leaks at the head or close to it (IE exhaust manifold gasket/crack in manifold) are often a sharp ticking sound, almost mechanical.
Buzzing like you describe is often a leak at the manifold/downpipe junction
the most common leak is between the downpipe and cat at the big doughnut gasket. This often manifests as a kind of puffing sound at idle.
Monday, December 18th, 2006 AT 5:34 PM