EGR VALVE TROUBLE SHOOTING: Let's look at some problems that can occur with your exhaust system. RUMBLING OR ROARING SOUND FROM UNDER THE HOOD AND/OR EXHAUST SMELL IN CAR: This is usually a sign of a worn exhaust manifold gasket. If gasket is okay, it is probably a cracked exhaust manifold or cracked front exhaust pipe. ROARING SOUND AT REAR OF CAR AND/OR EXHAUST SMELL IN CAR: This is likely a sign of a worn or leaking muffler or a leak at the rear exhaust pipe. To test for exhaust leaks, stuff a rag into the tail pipe and then start the car. If no leaks are evident, the rag will pop out or you will not be able to hold the rag in place. Be careful of a hot tail pipe.
