Exhaust Manifold Gasket Replacement

Few things are as annoying as the incessant sputtering of an automobile exhaust leak. Worse, the leak is often difficult to locate and sometimes only heard during hard acceleration, which makes it all but impossible to find while the vehicle is stationary. Fortunately, knowing a few simple tricks will help you quickly identify and correct problem areas.

Find The Leak
The most challenging task is separating the sound of the leak(s) from the roar of the engine. An inexpensive tool called a mechanic's stethoscope (available at most auto parts stores) is typically used to isolate metallic sounds emanating from individual engine components. For exhaust work, it helps to replace the solid probe portion of the stethoscope with a length of slender pipe or tubing, as you'll be listening for the rush of escaping exhaust gases and not the tapping of moving parts. Being very careful to avoid spinning belts and excessively hot areas, move the end of the tubing along mating areas while listening for the sound of rushing gases. You may have to temporarily remove some heat shielding to gain full access, but the testing will be over quickly and nearby components should not be damaged by the heat. With a steady hand and this modified tool, even minor exhaust leaks should be immediately apparent.

Replace The Gasket
Often the exhaust manifold gasket is the culprit, though gaps between catalytic converter flanges and rust holes in the muffler (from internal condensation) are also common. If the problem is at the exhaust manifold and there aren't any visible cracks, a basic gasket replacement should solve the problem. Let the engine cool fully and begin loosening the studs or nuts attaching the manifold to the engine's cylinder head. A quality, penetrating oil will help break the hardware free, though a professional mechanic should handle heavily corroded threads. Once the attaching hardware is removed, gently pull the manifold from the head studs. If resistance is encountered, check for additional brackets or mounting hardware further down the exhaust system that may be preventing manifold removal. Once the manifold is clear, remove all traces of the old gasket and clean the mating surfaces, ensuring that both are flat and will have a good seal against the new gasket. Slide on the new gasket, reinstall the manifold, and tighten attaching nuts and/or studs to factory torque specifications. Liberal use of anti-seize compound on the hardware threads will help resist corrosion and greatly ease future removal. After all components are reinstalled, give your exhaust system one final stethoscope inspection and enjoy your new blissfully quiet exhaust system!