TM 5-3810-300-24&P-3
7.0
SHOP NOTES-SPECIFICATIONS-SERVICE TOOLS
SHOP NOTES
INSTALLING A TEMPERATURE GAGE CAPILLARY TUBE
A temperature gage may register incorrect readings if the
and to the bulb. Also, whenever the tube is directed
capillary tube becomes damaged. Damage may occur if
around a corner, the bend should not be less than a
the tube has not been correctly installed and securely
one inch radius.
fastened to the engine. Factors such as sharp bends in
the tube and continuous vibration can cause a faulty
2. The tube should be adequately supported for its full
gage.
length to prevent excessive vibration. Fasten the
tube securely to the engine by means of metal clips.
To install a temperature gage on an engine correctly, and
The clips should be placed along the tube at
prevent any subsequent damage to the capillary tube,
intervals not exceeding ten inches.
the following precautionary steps must be taken.
3. Any extra length can be taken up by coiling; the
1. Avoid sharp bends in the tube, particularly at each
diameter of the coils should not be less than two
end where the tube is fastened to the gage
inches. The coils must be located so they may be
securely fastened to prevent vibration.
INSTALLING A TEMPERATURE GAGE CAPILLARY SWITCH
If difficulty in starting motor engagement has been
breaking of the solenoid current causes burning or
experienced in a vehicle which has been repowered by a
welding of the switch contacts.
diesel engine, check to see if the key-type starting switch
on the instrument panel has been retained.
Install a push button type starting switch which is capable
of making, breaking and carrying the solenoid current
Key-type starting switches are usually not capable of
without damage (refer to "Engine Starting Motor Switch"
carrying the current required for heavy-duty diesel engine
in Section 7.4). Otherwise, a heavy-duty magnetic switch
starter solenoids. The excessive voltage drop in the
should be used in the solenoid control circuit in addition
solenoid circuit restricts the solenoid pull and results in
to the key-type switch. The magnetic switch must be
failure of the starter to engage and crank. When tooth
capable of making and breaking at least 90 amperes in a
abutment occurs and the switch is turned off and on
12 volt system; the key switch would then carry no more
several times,
than one ampere, which is sufficient to operate the
magnetic switch.
CHECKING ENGINE ELECTRICAL GENERATING SYSTEM
Whenever trouble is indicated in the electrical generating
set too high or is not limiting the generator output. A high
system, the following quick checks can be made to
charging rate to a fully charged battery will damage the
assist in localizing the cause.
battery and other electrical components.
A fully charged battery and low charging rate indicates
A low battery and low or no charging rate condition could
normal generator-regulator operation.
be caused by: Loose connections or damaged wiring,
defective battery or generator (D.C. generator not or
A low battery and high charging rate indicates normal
improperly polarized), and defective regulator or
generator-regulator operation.
improper regulator setting.
A fully charged battery and high charging rate condition
usually indicates the voltage regulator is
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