An exhaust flex pipe is one component of the exhaust system in most vehicles.
The internal combustion engine in your vehicle relies on rapidly expanding gasses produced by burning fuel in order to propel the pistons and produce power. The combustion process, however, carries some unwanted byproducts in the form of harmful emissions (such as carbon monoxide, hydrocarbons, and nitrogen oxides), heat (as much as 1,000 degrees Fahrenheit), and noise. Therefore, an engine is fitted with an exhaust system to quiet down the sound of the engine and to route the engine exhaust away from vehicle occupants.
The exhaust system features a number of components fitted together in a configuration that snakes its way along your vehicle’s underbody. First, the hot and hazardous gasses are collected in the exhaust manifold as they exit the engine’s cylinders. From there, the exhaust passes through a pipe (the downtube) to the catalytic converter and ultimately to the muffler and out of the tailpipe at the rear of your vehicle.
Compared to most of the pipes that connect components of the exhaust system, the flex pipe is unique. It is usually made of braided stainless steel so that it can flex or move with the vibrations of your engine. Although it can be used in various applications in the exhaust system, it is typically mounted in the downpipe section of the system between the exhaust manifold and the catalytic converter.
The procedure to replace an exhaust flex pipe will depend on where the pipe is located and whether it is bolted or welded in place. If, for instance, the flex pipe is mounted between the exhaust manifold and the catalytic converter - and it is integrated into the down pipe - the entire section of exhaust pipe from the engine to the catalytic converter or beyond will need to be removed in order to cut out the old part and weld in a new one. That type of repair cannot be performed while the exhaust system is in place.
Since it is common for a flex pipe to be used in the down pipe section of the exhaust system, general steps to replacing the component might include: