SECTION 05: COOLING SYSTEM
8
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version – Rev.2 April 2016)
5.3 THAWING COOLING SYSTEM
If the cooling system becomes frozen solid,
place the coach in a warm area until the ice is
completely thawed.
CAUTION
Under no circumstances should the engine be
operated when the cooling system is frozen,
as it will result in engine overheating due to
insufficient coolant.
Once thawed, check engine, radiator and related
components for damage caused by expansion of
frozen coolant fluid.
5.4 COOLING SYSTEM RECOMMENDATIONS
Always maintain cooling system at the proper
coolant level. Check daily.
The cooling system must be pressurized to
prevent localized boiling of coolant. The system
must be kept clean and leak-free. The filler and
pressure caps must be checked periodically for
proper operation.
The coolant provides a medium for heat transfer
and controls the internal temperature of the
engine during operation. In an engine having
proper coolant flow, some of the combustion
heat is conveyed through the cylinder walls and
the cylinder head into the coolant. Without
adequate coolant, normal heat transfer cannot
take place within the engine, and engine
temperature rapidly rises. Coolant must
therefore be carefully selected and properly
maintained.
Select and maintain coolant in order to meet the
following basic requirements:
Provide for adequate heat transfer.
Provide protection from cavitation damage.
Provide a corrosion and erosion resistant
environment within the cooling system.
Prevent formation of scale or sludge
deposits in the cooling system.
Be compatible with the cooling system hose
and seal materials.
Provide adequate freeze protection during
cold weather operation.
When freeze protection is required, a mixture of
suitable water and antifreeze containing
adequate inhibitors will provide a satisfactory
coolant fluid.
Freeze
protection
down to:
Boiling up
protection to:
% of
antifreeze
in mixture
-10°F (-25°C)
-34°F (-38°C)
-62°F (-46°C)
259°F (126°C)
265°F (129°C)
270°F (132°C)
40%
50%
60%
5.5 COOLANT RECOMMENDATIONS FOR
MTA COACHES EQUIPPED WITH VOLVO
D13 ENGINE
Fleet Charge Fully formulated Coolant mixture
consisting of 50/50 antifreeze solution should be
used year-round to provide freeze and boil-over
protection as well as providing a stable
environment for seals and hoses.
When topping up coolant, use the same coolant
mixture type as the mixture already in the
cooling system. Do not mix two different types of
coolant.
Do not use antifreeze formulated for automobile
gasoline engines, these have a very high silicate
content that will clog the radiator and leave
unwanted deposits in the engine.
FIGURE 14: LOCATION OF HEATER LINE SHUT-OFF
VALVES IN ENGINE COMPARTMENT
05105
