How much? Are you losing coolant? If so, suspect a leaking head gasket. If it's clear water and it's dripping slowly from a small drain hole at the rear of the muffler, that is to prevent the muffler from rusting out early. Water is one of the byproducts of the catalytic converter doing it job to clean up the exhaust.
Friday, November 2nd, 2012 AT 1:11 AM