What does a bad exhaust gasket sound like?
What does a bad exhaust gasket sound like? A faulty exhaust manifold gasket will produce an exhaust leak that will sound like a hissing or tapping sound coming from the engine. The sound may be especially pronounced during a cold start or during acceleration. Why does my catalytic converter make a rattling noise? Ammonia (NH 3) odor may also indicate poor catalyst function. If the catalytic converter's housing is discolored or warped, there may be internal leakage or overheating. A rattling noise when starting the engine might indicate a broken catalyst. Failing the annual or semi-annual emissions test might also...