Engine
79
ENGINE COOLING
The heat generated by the engine is dissipated by a coolant solution that is circulated under pressure
within the cooling system. The cooling system includes the pump, radiator, surge tank, engine thermo-
stat, and the piping to connect the components. A fan powered by a hydraulic motor pulls air through the
radiator and over the engine for cooling.
The cooling system is filled through a filler cap on the surge tank. A pressure valve at the surge tank
maintains pressure within the cooling system. The thermostat is located in the thermostat housing on the
engine. When a cold engine is started or when the coolant temperature is below operating temperature,
the coolant flow to the radiator is blocked or restricted by the thermostat. A bypass provides coolant
circulation within the engine during the warm-up period.
Coolant from the engine pump is circulated through the transmission fluid cooler to absorb heat from the
transmission fluid. Refer to the Transmission chapter for coolant line connections at the fluid cooler.
The engine cooling system is also used to provide hot coolant for the coach driver heater/defroster and
passenger heating systems. Refer to the Climate Control chapter in this manual for information about
heating system coolant circulation.
Coo
lant Specifications
The proper coolant recommended for the engine is a solution of water and 45%–50% ethylene
glycol.
Coolant must meet ASTM 6210 specifications
(for more information, go to www.astm.org).
Coolant should also meet Cummins 14603 engineering specifications.
Call your Cummins Service
representative for information on this standard. Concentrations of ethylene glycol over 68% should
be avoided because of poor heat transfer capability, adverse freeze protection, and possible clogging
of engine coolant passages. An acceptable substitute for ethylene glycol coolant is a type made with
propylene glycol, provided the two types are never mixed.
Use of coolant made with methoxyl propanol is not recommended.
Methoxyl propanol can damage seals and hoses and creates a potential
fire hazard. Use of unapproved coolant may void the engine’s
warranty.
Do not add coolant made with propylene glycol to an engine cooling
system containing ethylene glycol coolant, or vice-versa.
The cooling system requires a supplemental coolant additive in addition
to the water/antifreeze coolant solution. Note specifications and
maintenance requirements in the following section.
Summary of Contents for LOW FLOOR
Page 18: ...Specifications 18...
Page 58: ...Preventive Maintenance 58...
Page 110: ...Engine 110...
Page 138: ...Transmission Driveline Rear Axle 138...
Page 182: ...Suspension 182...
Page 260: ...Air System 260...
Page 420: ...Electrical System 420 Deutsch DT Series Connectors...
Page 421: ...Electrical System 421...
Page 422: ...Electrical System 422 Deutsch HD 10 Series Connectors...
Page 423: ...Electrical System 423...
Page 424: ...Electrical System 424 Deutsch HD 30 Series Connectors...
Page 425: ...Electrical System 425...
Page 442: ...Heating Air Conditioning 442...
Page 492: ...Body and Interior 492 Figure 11 33 USSC Seat Assembly...
Page 493: ...Body and Interior 493 Figure 11 34 USSC Seat Suspension Assembly...
Page 495: ...Body and Interior 495 Figure 11 37 Seat Air Connections...