How long does it take for an old muffler to cause serious engine damage/problems?
if it’s a hole in the muffler than there’s no need to worry about it its not really an engine problem just an exhaust system problem that doesn’t affect the motor at all you might already have noticed an annoying sound while your driving because of the hole, all the exhaust system is a transfer system from the engine to the outside from the exhaust manifold (headers) exhaust fumes are passed to the catalytic converter where it gets heated further to lessen pollution to the environment and to burn up remaining fuel and then the muffler lets it all out.
