D
Group 177 Preventive Maintenance
Test Driving
112
Check After Start
Note: Some vehicles are equipped with TEMP-A-START
(TAS), which can be readily identified by a dash mounted
switch with a TAS indicator. Vehicles equipped with this
option will perform an engine shutdown if the engine is
left idling for 10 minutes, or a dash shutdown if the key
switch is left in the ignition position for 10 minutes with the
engine running. For more information on TAS, refer to
the vehicle literature.
Check Clutch Operation
Start the test drive by checking clutch pedal play and
clutch operation. Clutch pedal play should be 4 to 10 mm
(0.15 to 0.40 in.), which is the clearance between the
pedal plunger and the piston in the master cylinder.
On vehicles with clutch brake, check function by
depressing clutch pedal to within 6 to 12 mm (1/4 to 1/2
in.) from the floor while engaging a gear. There should
be no grating of the engagement teeth when the clutch
brake is engaged.
Check Parking Brake and Clutch Slip
Check for parking brake holding power and also for clutch
slippage by engaging direct gear, not allowing the engine
speed to go above 1,000 rpm and attempt to drive off
with the parking brake still applied. The parking brake
should hold the vehicle stationary while letting the clutch
up slowly.
If the clutch slips or the truck moves forward during this
operation, note on form for later inspection of either the
clutch or spring brake operation.
Release parking brake and start driving. Check that the
parking brakes are released quickly and that no brake
drag can be felt.
103
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