Chevrolet Low Cab Forward 6.0L Gasoline Engine 3500/4500 Series (GMNA-
Localizing-U.S.-12533400) - 2019 - CRC - 11/19/18
278
Service and Maintenance
19. BRAKE ELECTRIC VACUUM
PUMP (4500 Model) :
Inspect the
brake electric vacuum pump
operation every 12 000 km
(7,500 miles) or 12 months,
whichever occurs first.
How to check: This operation could
be difficult and you may choose to
have this done at your dealer
Service Department.
1. Turn the engine control switch to
the "ON" position (not to start the
engine), and press the brake pedal
several times.
2. Check for the noisy sound of the
electric vacuum pump inside the
instrument panel at the same time
as vacuum warning buzzer sound,
and check that the brake low
vacuum warning light comes on.
3. Then, after you start the engine,
the main vacuum pump driven by
the engine will start running. If the
electric vacuum pump operation
(noisy sound) and the vacuum
warning buzzer stop, and the brake
low vacuum warning light goes off
thereafter, the operation is normal.
4. If you cannot hear the noisy
sound of the electric vacuum pump,
check the electrical wiring and
repair as necessary. If it cannot be
repaired, replace the electric
vacuum pump.
20. BRAKE FLUID :
Check the fluid
in the brake fluid reservoir every
12 000 km (7,500 miles) and replace
fluid every 48 000 km
(30,000 miles).
21. BRAKE LINE AND HOSES :
Check lines and hoses for proper
hook-up, binding, leaks, cracks,
chafing, etc. every 48 000 km
(30,000 miles). Any questionable
parts should be replaced or repaired
at once. When rubbing or wear is
noted on lines or hoses, the cause
must be corrected at once.
22. HYDRAULIC UNIT :
Change
every 10 years.
23. DIFFERENTIAL GEAR OIL :
Replace lubricant every 48 000 km
(30,000 miles) or every 24 months.
Check lubricant level every
12 000 km (7,500 miles) or every
12 months, and add lubricant to
within 0 to 10 mm (0 to 0.4 inch) of
the bottom edge of the filler hole if
necessary.
24. POWER STEERING FLUID :
Replace power steering fluid every
24 months or 60 000 km
(37,500 miles), whichever occurs
first.
25. STEERING WHEEL FREE
PLAY :
Check steering wheel free
play after the first 1 040 km
(650 miles) and then every
10 400 km (6,500 miles).
Steering wheel free play
10-50 mm (0.39-1.97 in)
26. STEERING GEAR BOX
TORQUE :
Retighten the fixing bolts
of the steering gear box to the
specified torque every 48 000 km
(30,000 miles). Specified tightening
torque.
Steering gear box tightening
torque
102
Y
(75 lb·ft)
