MUFFLER

The muffler (fig. 4-49) reduces the acoustic pressure of exhaust gases and discharges them to the atmosphere with a minimum of noise. The muffler usually is located at a point about halfway in the vehicle with the exhaust pipe between it and the exhaust manifold and the tailpipe leading from the muffler to the rear of the vehicle.

The inlet and outlet of the muffler usually is slightly larger than their connecting pipes, so that it may hook up by slipping over them. The muffler is then secured to the exhaust pipe and tailpipe by clamps.

A typical muffler has several concentric chambers with openings between them. The gas enters the inner chamber and expands, as it works its way through a series of holes in the other chambers and finally to the atmosphere. They must be designed also to quiet exhaust noise while creating minimum back pressure. High back pressure could cause loss of engine power and economy and also cause overheating.

Exhaust system components usually are made of steel. They are coated with aluminum or zinc to retard corrosion. Stainless steel also is used in exhaust systems in limited quantities due to its high cost. A stainless steel exhaust system will last indefinitely.