GMC TopKick 2007 Owner's Manual page 299

Electric Air Compressor
Your vehicle may have an electric air compressor.
This compressor is used to run options that
require pressurized air, such as an air horn, air
seat, 7.8L engine exhaust restrictor, or 7.8L engine
exhaust brake.
The air compressor is used when vehicles do not
have an air brake system.
It is recommended that this system be drained on
a weekly basis.
The air supply for
this system must be
maintained by releasing
the drain valve to eject
any moisture that may
have built up in the
system.
Clutch Pedal Free Travel
If you have a V8 engine and a manual transmission,
the clutch will need adjustment when pedal free
travel gets down to about 1/4 inch (6 mm), as
measured at the clutch pedal pad. You should
have 1 1/2 to 2 inches (38 to 51 mm) of clutch
pedal free travel.
If the clutch ever needs service, be sure to use
only GM clutch replacement parts.
Chassis Lubrication
Your Maintenance Schedule provides all of
the required chassis lubrication intervals and
identifies proper lubricants to use. Be sure to
see the Maintenance Schedule before performing
any chassis lubrication service. To determine
location of chassis lubrication items, use the
following charts.
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