Chevrolet 1980 Light Duty Truck Service Manual page 22

OB-12 M A INTENA NCE A N D LUBRICATION
range. Sustained driving at speeds over 85 mph
(140 km /h), w here such speeds are permitted by
unless vehicle is equipped with
law, is not advised
special high speed.
Truck-Type Tires:
For sustained driving at speeds over 65 mph
(1 0 0 km /h), w here such speeds are permitted by
law cold inflation pressures should be increased
10 psi (70 kPa) above those stated in the T ire /
W heel Load and Inflation Pressure Charts for the
load being carried. Do not exceed the wheel
capacity lim it shown in Section 3E.
Sustained speeds over 65 mph (100 km /h) are
where the 10 psi (70 kPa) pressure increase
not advised
would exceed the wheel capacity limit.
For special operating conditions, such as carrying slide-
in campers, cold inflation pressures may be increased up to
10 psi (70 kPa) above those shown in the table. The total
increase in cold inflation pressures, however, must not
exceed the wheel capacity limit shown in Section 3E.
Passenger-car-type tires
millimeter) or smaller wheel size and have no "LT"
designation molded in the sidewall after the tire size. Light
truck-type tires have "LT" molded in the sidewall after the
tire size and/or are larger than 15 inches (380mm) in wheel
size.
Passenger-Car Type Snow Tires:
When using passenger-car-type snow tires, cold
inflation pressures should be increased 4 psi (30 kPa) above
the stated cold inflation pressures on the Certification Label
up to the maximum for each load range stated in the chart
above. Sustained speeds above 75 mph (120 km /h)
are not advised.
CAUTION: Be sure to keep tires properly
inflated. A tire
significantly underinflated w ill overheat
to the point w here the tire may blow out
and/or catch fire, possibly resulting in
damage to the vehicle and its contents
and/or personal injury to its occupants
and persons in the area.
Truck-Type Snow Tires:
When using truck-type snow tires, cold inflation
pressures should be increased 10 psi (70 kPa) above the
advised pressures for the load being carried. However, do
not exceed the wheel capacity limit shown in Section 3E.
3. For proper inflation pressures when towing trailers,
the following is recommended:
When towing trailers on dead-weight hitches, inflate
tires to the pressures shown on the Certification Label (on
either the left door latch post or the left door edge next to
the driver) or, if applicable the "Tire Inflation Pressure"
charts in Section 3E.
For trailers using weight-distributing hitches, increase
front tire pressure 2 psi (14 kPa) above the pressure shown
on the Certification Label (or "Tire Inflation Pressure"
charts). This increase should never exceed the maximum
pressure shown on the side of the tire.
It should be remembered that when a trailer is
connected, the trailer tongue weight is part of the load being
have a 15-inch (380
th a t is run while
carried by the vehicle and, therefore, is included in the
GVW of the vehicle.
4. Always use a tire pressure gage (a pocket-type gage
is advised) when checking inflation pressures. A visual
inspection of tires for inflation pressures is not enough,
especially in the case of radial tires. Underinflated radial
tires may look similar to correctly inflated radial tires. If
the inflation pressure on a tire quite often is found to be low,
correct the cause.
5. Be sure to reinstall the tire inflation valve caps, if
so equipped, to prevent dirt and moisture from getting into
the valve core which could cause air leakage.
6. If an air loss occurs while driving, do not drive on
the deflated tire more than is needed to stop safely. Driving
even a short distance on a deflated tire can damage a tire
and wheel beyond repair.
A-8 Rear Axle
Drain and refill to level of filler plug hole every 7,500
miles (12 000 km) on light duty emissions or 12,000 miles
(19 200 km) on heavy duty emissions when using vehicle
to pull a trailer or severe operating conditions. Use SAE
80W GL-5 or SAE 80W-90 GL-5 gear lubricant. In Canada,
use SAE 80W GL-5 gear lubricant. On 20 and 30 series
trucks, change lubricant every 24,000 miles (38 400 km).
A-9 W heel Bearing
For normal application, clean and repack front wheel
bearings with a high melting point wheel bearing lubricant
at each front brake lining replacement or 30,000 miles (48
000 km) on light duty emissions 12,000 miles (19 200 km)
on heavy duty eymission or 15,000 miles (24 000 km) on
diesel engine vehicles which ever comes first. For heavy
duty application such as police and taxi cabs, clean and
repack front wheel bearings at each front brake lining
replacement or 15,000 miles (24 000 km) which ever comes
first.
Use Wheel Bearing Lubricant GM Part No. 105
(one pound), 1052356 (35 pounds) or Exxon Ronex
Grease or equivalent. This is a premium high melting point
lubricant.
"Long fiber" or "viscous" type lubricant should not be
used. Do not mix wheel bearing lubricants. Be sure to
thoroughly clean bearings and hubs of all old lubricant
before repacking.
Tapered roller bearings used in this vehicle
NOTICE:
have a slightly loose feel when properly adjusted. They
must never be over tightened (preloaded) or severe
bearing damage may result.
Refer to Section 3C for proper detailed adjustment
procedures and specifications.
A-10 Cooling System
(Also a LD Emission Control Service)
The coolant recovery system is standard. The coolant
in the radiator expands with heat, and the overflow is
collected in the recovery tank. When the system cools down,
the coolant is drawn back into the radiator.
The cooling system has been filled at the factory with
a quality coolant that meets General Motors Specification
1899-M. The coolant is a 50/50 mixture of water and
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LIG H T DUTY T R U C K S E R V IC E M AN U AL