TM 5-3825-213-35
CHAPTER 3
ENGINE HEATER REPAIR INSTRUCTIONS
Section I. CARRIER AND PLOW ENGINE HEATERS
54. General
b. Inspection and Repair.
(1) Inspect for defective power, preheat, and
a. Description. There are two electrically
nonfire relay; ignition coil assembly, fuel
controlled, gasoline-operated, coolant heaters which
regulator valve and nozzle assembly,
preheat the engine coolant before starting under
flame switch, and contact plate on the
conditions of extreme cold. The carrier engine heater is
control head.
mounted on the carrier frame in front of the carrier
(2) Inspect for a defective combustion fan
engine hood. The plow engine heater is mounted on the
and motor, combustion chamber, and
plow clutch housing cover in back of the plow engine
heater housing.
hood.
(3) Repair or replace all defective parts.
b. Fuel System. Fuel to operate the heaters is
drawn from the carrier fuel tank. Each heater has a fuel
c. Testing.
filter, electrical fuel pump, and an electrically operated
(1) Flame switch. Disconnect all leads from
regulating valve which controls the flow of fuel.
the flame switch (27, fig. 8). Check the
c. Electrical System. The heater electrical system
continuity of the circuits through the flame
controls the operation of the fuel and air systems
switch with a test light and probe, or an
throughout the complete heater cycle. The control box,
ohmmeter. Use the wiring diagram (TM
located in the carrier cab, controls the circuits from the
5-3825-213-20) when making these
power source to the heater and fuel pump.
checks. Apply heat to the flame switch
tube. The switch should change to hot
55. Carrier and Plow Engine Heaters Removal and
position at 400 to 500 F. Continuity
Disassembly
should now be across terminals 1 and 2
and terminals 1 and 5. Allow the tube to
cool. The switch should return to cold
a. Removal.
position at 200 to 300 F.
(1) Remove the engine heater (TM 5 3825-
(2) Blower motor. Connect a power supply
213-20).
with the motors specified dc voltage to the
(2) Remove control panel cover and igniter
assembly and operate the motor. With a
(TM 5-3825-213-20).
tachometer check the motor speed. The
minimum rpm for the circulating air blower
b. Disassembly. Disassemble the engine heaters
motor is 3,700. Combustion air blower
motor 6,500. The motor speed should be
equal to or greater than specified rpm for
56. Carrier and Plow Engine Heaters Cleaning,
particular unit tested.
Inspection, Repair, and Test
57. Carrier and Plow Engine Heaters Reassembly
a. Cleaning. Clean all parts with an approved
and Installation
cleaning solvent and dry thoroughly.
a. Reassembly.
(1) Reassemble the engine heaters in the
reverse of the numerical sequence
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