freightliner Custom Classic MT45 2022 Maintenance Manual page 45

Engine Cooling/Radiator
20–00 Safety Precautions
Safety Precautions in this section apply to all
procedures within this group.
DANGER
When working on the vehicle, shut down the en-
gine or motor, set the parking brake, and chock
the tires. Before working under the vehicle, always
place jack stands under the frame rails to ensure
the vehicle cannot drop. Failure to follow these
steps could result in serious personal injury or
death.
20–01 Coolant Replacement
At the intervals specified in the maintenance sched-
ule, or whenever the coolant becomes dirty, flush
and refill the cooling system as follows, based on the
type of engine installed in the vehicle.
Diesel Engine
WARNING
Never remove the surge tank cap while the engine
is operating or while the engine and radiator are
still hot. Scalding fluid and steam can blow out
under pressure if the cap is taken off too soon.
Failure to follow these precautions could result in
serious personal injury from heated coolant spray.
1. When the engine is cool, remove the surge tank
cap.
Turn the cap slowly counterclockwise until it
reaches a "stop." Do not press down while turn-
ing the cap. Wait until any remaining pressure
(indicated by a hissing sound) is relieved, then
press down on the cap and continue turning it
counterclockwise.
2. When the cap is removed, run the engine until
the upper radiator hose is hot. This shows that
the thermostat is open and that the coolant is
flowing through the system.
Walk-In Van Chassis Maintenance Manual, January 2022
WARNING
Drain the coolant only when the coolant and en-
gine are cool. Draining it when these are hot could
cause severe personal injury due to scalding.
3. Shut down the engine. Remove the lower radia-
tor hose and drain the coolant. Draining may be
speeded up by removing the plug from the bot-
tom of the water inlet.
NOTICE
During filling, air must be vented from the engine
coolant passages. Any air trapped in the system
can cause severe engine damage.
4. Connect the lower radiator hose and install the
plug in the bottom of the water inlet. Add water
until the system is filled and run the engine until
the upper radiator hose is hot again. The system
must be filled slowly to prevent air locks. Wait 2
to 3 minutes to allow air to be vented, then add
water to bring the level to the top.
5. Repeat the last two steps several times until the
drained liquid is nearly colorless.
6. Drain the system, then close the radiator and
block the drain valves.
7. Disconnect all hoses from the coolant surge
tank. Remove the surge tank and pour out any
fluid. Scrub and clean the inside of the surge
tank with soap and water. Flush it thoroughly
with clean water, then drain it. Reinstall the surge
tank and hoses.
IMPORTANT: The coolant capacity varies de-
pending on the engine and accessory installa-
tion. After servicing the cooling system, always
verify that the coolant level is between the MIN
and MAX lines on the surge tank.
8. Fill the cooling system.
8.1 Slowly add a 50/50 mixture of antifreeze
and water to the surge tank; no more
than 3.0 gallons per minute (gpm). Fill to
the top of the surge tank. For approved
coolants, refer to the coolant label on the
vehicle or the engine manufacturer's ser-
vice literature.
8.2 With the radiator cap removed, start the
engine and run it at low idle for 1 minute;
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