TM 5-6115-593-12
TO 35C2-3-463-1
instrument reaches approximately 120F 5
(50°C 2).
(d)
As the water begins to cool, note that heater
automatically comes on at approximately
100°F 5 (38C 2).
(e)
If switch fails to meet above test, it should
be replaced.
(f)
Open both shutoff cocks.'
(2)
Heater H101, H102 and H103 (18 and 53, figure
4-30).
(a)
Place EXTERNAL POWER BREAKER and
PREHEAT switch to the off position. (figure
2-10).
(b)
Locate
terminal
board
within
heater
electrical enclosure (40 figure 4-30) and
remove wires X173H and X174H from
terminal points 6 and 7. Isolate 12 gauge
and 14 gauge wires from terminal point 7.
(c)
Using an ohmmeter, check resistance be-
tween terminal point 4 and 12 gauge wire
isolated from terminal point 7. Resistance
should be 8.0 ohms. Resistance between
terminal point 4 and 6 should also be 8.0
ohms. Resistance between terminal point 4
and 14 gauge wire isolated from terminal
point 7 should be 50 ohms. (Refer to
Engine Accessories Wiring Diagram FO-11)
(d)
If the above tests are not met, one or more
of the heater elements are defective and
must be replaced.
c.
Replacement.
CAUTION
Shut off engine/generator set and allow
sufficient time for engine coolant to cool
before handling hoses and fittings. Use
suitable containers to prevent loss of
coolant. Switch off EXTERNAL POWER
BREAKER.
(1)
Close both shutoff cocks (4), drain coolant
from preheat system by disconnecting
heater hose going to highest point on engine
and
carefully
lowering
into
suitable
container.
(2)
To
remove
coolant
heater
assembly,
remove the wires going to heater element
(18) and (53). Remove heater coolant
hoses. Remove four bolts, nuts and washers
(34).
(3)
To remove oil heater, oil must first be
drained from oil sump. Remove bell cap
(38) then disconnect wires from end of
heater element. Refill engine crankcase with
oil once heating element has been replaced.
(4)
Open both shutoff cocks when coolant
heater repair or replacement have been
accomplished.
4-83
