freightliner COLUMBIA CL112 Maintenance Manual page 42

Engine Cooling/Radiator
20–01 Pressure Relief Cap
Check
WARNING
Do not remove or loosen the surge tank cap until
the engine and cooling system have completely
cooled. Use extreme care when removing the cap.
A sudden release of pressure from removing the
cap prior to the system cooling can result in a
surge of scalding coolant that could cause seri-
ous personal injury.
1. Remove the fill cap, first, to relieve the cooling
system pressure, then remove the SAE cap.
2. Using a radiator-cap tester, check the pressure
cap to see if it maintains pressure to within 10%
of the pressure rating marked on the cap. If it
doesn't, replace the cap. See
that the replacement radiator cap is correctly
rated for the cooling system of the vehicle.
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06/08/95
1. Low-Coolant-Level Sensor
2. SAE Cap (for coolant overflow pressure relief only)
3. Fill Cap
Columbia Maintenance Manual, January 2007
Fig. 1. Make sure
2
Fig. 1, Surge Tank
3. There is a second valve in the radiator cap that
opens under vacuum. This prevents the collapse
of hoses and other parts that are not internally
supported when the system cools. Inspect the
vacuum-relief valve to be sure it is not stuck.
4. Make sure that the cap seals properly on the
coolant filler neck seat, and that the radiator cap
gasket is not damaged. On vehicles with
screw-on caps with O-rings, make sure that the
O-ring is not cracked or deteriorated. Replace
the cap if the gasket shows deterioration or dam-
age.
20–02 Radiator Pressure-
Flushing and Coolant
Change
NOTE: For additional instructions on cleaning
and flushing the engine cooling system, see the
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