Even though the system has been purged of DEF
there are small quantities of DEF that can be left
behind. The DEF supply line, suction, and the back
flow line are heated to thaw any remaining DEF in the
lines. The heated lines will prevent restrictions in the
pump and injector once the system begins to dose.
The heated lines have the following characteristics.
• Thermoplastic core tube with fabric reinforcement
• Stainless steel heating wire
• Extruded thermoplastic jacket
• Heat/abrasion shield
• Quick disconnect connector
Cold-Weather Operation
Since DEF freezes at −11.5° C (11.3° F), the system
can thaw the DEF before dosing.
Engine coolant is supplied to the PETU. The coolant
diverter valve will turn on anytime the DEF Tank
temperature is less the 15° C (59° F) at start-up.
During operation, if the DEF tank temperature drops
below 20° C (68° F) or ambient temperature falls
below 0° C (32° F) then the coolant diverter valve will
activate to keep the DEF from freezing. The tubes
running through the tank will thaw the DEF to a
useable temperature. Then DEF dosing will occur
once the DEF has been thawed and the DEF tank
temperature is greater than −8° C (18° F). The DEF
dosing will not wait for the entire tank to thawed. The
DEF pump is heated by an internal heating element.
The coolant will then return to the engine water pump
inlet. The DEF supply lines, suction lines, and
backflow lines are heated electrically.
The DEF dosing system must be fully functional
within 70 minutes following initial start-up.
Note: If the DEF has not been removed from the
lines and pump during cold-weather operation, the
DEF will expand as the fluid freezes and damage the
pump. For this reason the purge process must be
followed in cold weather. Refer to Operation and
Maintenance Manual, “Battery Disconnect Switch” for
more information. Do NOT turn off battery power until
this pump has completed the purge cycle.
i04135351
Cooling System
Introduction
The cooling system has the following components:
• Radiator
• Water pump
• Cylinder block
• Oil cooler
• Exhaust gas cooler (NRS)
• Cylinder head
• Water temperature regulator
UENR4490-01 35
Engine Operation
This document has been printed from SPI2. NOT FOR RESALE
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