This car sits in the college parking lot most of the week. It is an Elantra GT, 1.8 4 cyl. with dual over head cam and 16 valves. 139000 miles. It has been a decent car until recently when the transmission went and got it replaced, and now the engine is tapping, loudly at first then slow and more rythmically as it idles. My son says it gets louder when driving. Mechanics at AAA car service says new engine is needed. Anything I can do to make it last at least a year, or to quiet it down for a while? Without it costing 4 grand (more than its wort:h) for a new engine. Thanks in advance.