The additional muffler is also different - its front pipe is shorter and has a flange for mounting the neutralizer. The mufflers and neutralizer are non-separable units and should be replaced with new ones when they fail.
The exhaust manifold is cast from cast iron. A metal-reinforced heat-resistant gasket is installed between it and the cylinder head. The intake pipe is attached to the manifold with four studs. The connection is sealed with a heat-resistant gasket. The fastening nuts are brass or copper-plated and are secured from unscrewing with locking plates (one for two nuts), the edges of which are bent at the edge of the nuts. The inlet pipe is additionally attached with a clamp to the bracket on the gearbox.
On cars with carburetor engines, the muffler pipes are pushed into each other and secured with clamps. On cars equipped with an injection system, the connections of the neutralizer with an additional muffler and an inlet pipe are flanged, the front one is with a ball joint (the pipes can rotate relative to each other at a small angle without losing their tightness), its mounting bolts are spring loaded.
The neutralizer serves to reduce emissions of carbon monoxide and nitrogen oxides into the atmosphere. It consists of two ceramic blocks with many pores, coated with so-called afterburning catalysts: rhodium, palladium, platinum. Passing through the pores of the neutralizer, toxic carbon monoxide (CO) is converted into low-toxic dioxide (CO ₂), and nitrogen oxides are reduced to harmless nitrogen. The degree of gas purification in a serviceable neutralizer reaches 90-95%. For normal operation of the neutralizer, the composition of the exhaust gases (in particular, their oxygen content) must be within strictly specified limits. This function is performed by the controller, changing the amount of fuel supplied depending on the readings of the oxygen sensor (see Injection engine control system). The neutralizer and oxygen sensor are very sensitive to lead compounds - "poisoned" by them, they stop working. Therefore, if the car is equipped with a neutralizer, its operation is strictly prohibited (even short-term) on leaded petrol. Another reason for the failure of the neutralizer is interruptions in the ignition system: unburned fuel burns out in the neutralizer, damaging the ceramics. This can lead to blockage of the exhaust system and engine stalling (or severe loss of power).
The main muffler is located in a niche in the rear part of the body. It is attached to the body brackets on two rubber cushions. The middle part of the exhaust system (with additional muffler) has no attachment points to the body. To protect the body floor from excessive heating, a protective screen is attached above the main muffler.
Maintenance of the exhaust system consists of periodic inspection of pipes and mufflers for corrosion and tightening or replacing loose connections.
The source is on the website VazBook.ru