ARMY TM 9-6115-604-12
NAVY NAVFAC P-8-633-12
a.
Remove.
(1)
Using a drain or sump, drain the radiator partially in accordance with paragraph :3-12.
(2)
Tag and disconnect electrical connectors from switch. Remove switch.
b.
Test.
(1)
Connect a multimeter set to RX1 scale across switch contacts.
(2)
Suspend switch in a container of antifreeze. Switch should be inserted so that sensing element is
completely immersed but connector end is out of antifreeze. Put positive lead of a 24 V dc power
supply to positive (+) terminal and the negative (-) lead of a 24 V dc power supply to the switch metal
frame (ground).
(3)
Switch should be open and the multimeter should read infinite ohms.
(4)
Remove the switch from the antifreeze. The contacts should close and the multimeter should read
less than 1 ohm.
(5)
The switches are not repairable. If they do not operate within above limits, they must be replaced.
c.
Install.
(1)
Install switch and restore electrical connections as tagged. Discard tags.
(2)
Refill radiator. Check for leakage around switch and tighten as necessary.
4-26.
MAINTENANCE OF LUBRICANT OIL TEMPERATURE SWITCH OT2 . Lubricant oil temperature switch OT2
(see Figure 3-3) senses engine lubricating oil temperature. When lubricating oil temperature exceeds 245 ± 3°F
(118.3 C) the normally open contacts close. This action results in a warning only.
a.
Remove.
(1)
Drain the oil pan in accordance with paragraph 3-3.
(2)Tag and disconnect electrical connectors from switch. Remove switch.
b.
Test.
(1)
Connect a multimeter set to RX1 scale across switch contacts.
(2)
Suspend switch in a container of antifreeze. Switch should be inserted so that the sensing element is
completely Immersed but connector end is out of antifreeze.
Exercise extreme care when heating antifreeze or handling antifreeze. Avoid
spilling. Antifreeze may cause severe burns.
(3)
Heat antifreeze gradually and stir so that heat is evenly distributed.
(4)
Check temperature of antifreeze with a reliable thermometer.
(5)
When antifreeze has reached 245 ± 3°F (118.3 C) the switch should close and the multimeter should
read less than 1 ohm.
(6)
Allow antifreeze to cool. As the temperature drops the switch should open and the multimeter should
read infinite ohms.
(7)
The switch is not repairable. If It does not operate within the above limits, it must be replaced.
c.
Install . Clean switch thoroughly and proceed as follows:
(1)
Install switch and restore electrical connections. Discard tags.
(2)
Refill oil pan in accordance with paragraph 3-3.
(3)
Check for leakage around switch; tighten as necessary.
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