MBE4000 APPLICATION AND INSTALLATION
□
Special vents which may be required to ensure excessive air can be purged during system
fi
ll, if components are mounted above the coolant level. The engine
must
be run after the
system has been
fi
lled to purge any remaining trapped air. Add makeup coolant as required.
Speci
fi
c considerations are as follows:
□
Connect auxiliary oil coolers and retarder heat exchangers in series with the main coolant
fl
ow on the pressure side of the pump. Coolers located on the inlet side of the water
pump require modi
fi
cations to the engine water bypass circuit to provide coolant
fl
ow
through the cooler during closed thermostat operation. Modi
fi
cations
must not
hinder air
from being purged from the water pump. Engine coolant warm-up problems may occur
when coolers are located in the radiator bottom tank. Connect the heater supply at the
water pump discharge and the return to the thermostat housing base. See the installation
drawings for speci
fi
c locations.
□
Give special care to excessively cold ambient operating conditions.
□
Enhance driver/passenger comfort through the use of highly ef
fi
cient, low restriction heater
cores. Highly ef
fi
cient, modern engines reject less heat to the coolant. It may be necessary
to increase idle speed to maintain coolant temperatures.
Water Pumps
A water pump is used to circulate the coolant throughout the cooling system, including customer
add-on features such as cab heaters,
fi
lters, and auxiliary oil coolers. Pumps are sensitive to
inlet restrictions, coolant temperature, coolant type and aerated coolant. Discharge
fl
ow can
be seriously reduced and damaging cavitation can occur if the cooling system is not designed
properly.
Water pump inlet restriction
must
be kept to a minimum to prevent cavitation. This means
radiators, auxiliary oil coolers located between the radiator and the pump inlet (not preferred
location), as well as the associated plumbing
must
introduce minimal restriction. Lines connected
to the water pump inlet
must
have at least the same area as the pump inlet. Bends should be kept
to a minimum and they should have a generous radius (no mitered bends). The water pump inlet
pressure (suction)
must not
exceed allowable limits The actual limits is listed in the “Technical
Data” section of this manual (refer to section 14). The lowest pressure in the entire cooling
system is found at the water pump inlet. This pressure can be below atmospheric; thus cavitation
(boiling) will occur below 100°C (212°F) at sea level. Altitude causes higher probability of
cavitation in cooling systems.
The pump can easily become air bound if a large volume of air is trapped in the pump during
coolant
fi
lling, or if air is fed to the pump when the pump is running. Vehicle heater systems can
be a major source of air. Air can also be introduced into the cooling system from a severely
agitated or improperly designed top tank.
All information subject to change without notice.
(Rev. 03/06)
7-23
7SA250 0603
Copyright © 2006 DETROIT DIESEL CORPORATION