Description - GMC G Service Manual

SUBJECT
Description.................................................................................................................................................................. 6F- 1
Diagnosis of Exhaust System...................................................................................................................................6F- 2
On-Vehicle Service..................................................................................................................................................... 6F- 2
Inspection................................................................................................................................................................ 6F- 2
Installing Exhaust Parts......................................................................................................................................... 6F- 2
Catalytic Converter Replacement..........................................................................................................................6F- 4
Specifications............................................................................................................................................................. 6F-10
Torque Specifications............................................................................................................................................ 6F-10
Exhaust system designs will vary according to model
designation and intended use of the vehicle.
The exhaust system uses a ball joint coupling to secure
the exhaust pipe to the engine manifold. The ball joint will
allow angular movement for alignment purposes. The other
connections use a slip joint coupling design with a clamp
and U-bolt.
The exhaust system is suspended by hangers attached
to the frame members. This will permit some movement of
the exhaust system, but should not permit the transfer of
noise and vibration into the vehicle.
Heat shields are used to protect both the vehicle and the
environment from the high temperatures developed from
the exhaust system, especially the catalytic converter.
SECTION 6F
EXHAUST
CONTENTS

DESCRIPTION

The catalytic converter is an emission control device
added to the gasoline engine exhaust system to reduce
hydrocarbon and carbon monoxide pollutants from the
exhaust gas stream. The converter contains beads which
are coated with a catalytic material containing platinum and
palladium. The catalytic converter for the computer com­
mand control emission system will also contain rhodium to
reduce the level of nitrogen oxides. The catalyst in the con­
verter is not serviceable.
THE CATALYTIC CONVERTER REQUIRES THE USE
OF UNLEADED FUEL ONLY.
The diesel engine does not use a catalytic converter,
and uses only diesel fuel.
6F-1
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