Manifold and exhaust system - K Series 1.8 (Description): Description and operation

Description

Inlet Manifold

The inlet manifold is a one piece plastic moulding which is attached to the cylinder head on six locating studs and nuts and further retained by one bolt. A rubber moulded gasket, which is located in a corresponding recess in the inlet manifold mounting face, seals the manifold to the cylinder head.

The inlet manifold has vacuum take-off points for the fuel pressure accumulator, the brake servo and the purge valve. A further take-off point vents the camshaft cover into the inlet manifold.

Two threaded lugs on the inlet manifold provide for the attachment of the fuel rail. Four ports at the base of each inlet tract house the injectors which are sealed to the manifold with 'O' ring seals and retained in position by the fuel rail.

The Idle Air Control (IAC) valve is attached to the inlet manifold, adjacent to the throttle housing and is secured with four Torx bolts and sealed to the manifold with an 'O' ring seal.

The throttle housing is attached to the left hand end of the inlet manifold and is secured with four bolts and sealed with an 'O' ring seal. The Intake Air Temperature (IAT) sensor is mounted in No. 4 inlet tract.

Exhaust Manifold

The exhaust manifold is a fabricated and welded steel construction. The four branch manifold is located on five studs in the cylinder head and secured with five nuts. A metal corrugated gasket seals the exhaust manifold to the cylinder head. The four separate branches of the manifold merge into one at a starter catalytic converter. The starter catalytic converter is fitted with a flange which mates with the exhaust system front pipe and is sealed with a metal gasket. Two captive studs in the manifold pass through the mating flange of the front pipe and are secured with nuts.

A threaded boss above the starter catalytic converter allows for the fitment of a pre-catalyst Heated Oxygen Sensor (HO2S). The HO2S measures the oxygen content of the exhaust gases before they enter the starter catalyst.

Exhaust System

The exhaust system comprises of a front pipe assembly incorporating a catalytic converter, intermediate pipe assembly and a tailpipe assembly.

Front Pipe Assembly The front pipe assembly is of welded and fabricated tubular construction and is connected to the exhaust manifold flange studs with two nuts and sealed with a metal gasket. A single pipe from the flange is positioned below the engine and connects into an integral flexible pipe section.

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

From the flexible pipe a short section of pipe is welded to the main catalytic converter. A second piece of pipe is welded to the outlet from the catalytic converter and incorporates a flange with two captive studs which mate with the intermediate pipe assembly. EMISSION CONTROL - K SERIES 1.8, DESCRIPTION AND OPERATION, Description.

CAUTION: Ensure the exhaust system is free from leaks. Exhaust gas leaks upstream of the catalytic converter could cause internal damage to the catalytic converter.

Two support brackets are welded to the pipe and support the front pipe assembly via mounting rubbers to brackets on the body.

Intermediate Pipe Assembly A flange at the forward end of the intermediate pipe connects to the front pipe flange and is secured with two nuts and sealed with a metal gasket. A fabricated, circular silencer is mounted at the forward end of the intermediate pipe assembly. The rear pipe from the silencer is shaped to go around and over the rear subframe and terminates in an open end which mates with the tail pipe assembly. The intermediate pipe assembly is not attached to the vehicle body, but is retained by the flanged joint on the front pipe and the clamp on the tail pipe assembly.