Manifold & exhaust systems (Exhaust system): Description and operation

EXHAUST SYSTEM

’K’ Series Engine

The exhaust system comprises of a catalytic converter, centre silencer assembly and a tailpipe. The system is constructed of extruded pipe with a 1.5 mm wall thickness.

Front Pipe Assembly

The downpipe assembly is of welded and fabricated tubular construction. The downpipe is connected to the exhaust manifold flange with four nuts and sealed with a metal gasket. Two pipes from its mounting flange merge into one pipe halfway along its length. The pipe then connects into a flexible pipe and terminates in a flanged connection.

The flexible pipe is formed into a concertina shape with woven metal strands around its outer diameter. The flexible pipe allows for ease of exhaust system alignment and also absorbs engine vibration. The woven metal strands increase the longevity of the flexible pipe.

The front pipe is secured with two brackets bolted to the engine sump plate and the intermediate reduction drive and a mounting rubber connected to the body.

Catalytic Converter (CAT)

The CAT is mounted between the front pipe and the centre silencer assembly. A flange is welded to each end of the CAT with three captive bolts in each flange. The CAT connects to mating flanges on the front pipe and centre silencer and is secured with nuts. Metal gaskets seal each flanged joint.

NOTE: Refer to the Emissions section for a description and operation of the catalytic converter.

CAUTION: The catalytic converter will be irreparably damaged if leaded fuel is used. Leaks in the exhaust system will also damage the catalyst by drawing oxygen into the exhaust system which causes the catalyst to overheat. Engine misfires cause overheating of the catalyst which may lead to irreparable damage.

Intermediate Pipe Assembly

A fabricated silencer is mounted at the forward end of the intermediate pipe assembly.A flange at its forward end connects to the catalytic converter flange and is secured with three nuts and sealed with a metal gasket. The rear pipe from the silencer is shaped to go around and over the rear subframe. The flanged end is connected to the vehicle body with a mounting rubber. The silencer is fabricated from 0.6 mm mild steel outer tube with a 0.5 mm stainless steel inner liner. An end plate is secured at each end of the outer tube with seam joints. A perforated baffle tube is welded to each end plate. A stainless steel fibre is packed between the baffle tube and the inner liner to absorb engine noise as exhaust gases pass through the silencer.