TM 5-3895-359-14&P
system, including cooling system bleed holes and water
the coolant at prescribed intervals to maintain original
pump drain holes.
strength levels.
Always follow the supplier's
recommendations on inhibitor usage and handling.
GENERAL RECOMMENDATIONS
TEST STRIPS
All Detroit Diesel engines incorporate pressurized
cooling systems which permit operation at temperatures
Some chemical manufacturers have developed test
higher than non-pressurized systems. It is essential that
strips for use with their antifreeze or coolant additives.
these systems be kept clean and leakfree, that filler
These test strips are used to measure the freeze
caps and pressure relief mechanisms be correctly
protection and/or inhibitor strength of ethylene glycol-
installed at all times and that coolant levels be properly
based antifreeze. To avoid a false reading caused by
maintained.
variations in reserve alkalinity, Detroit Diesel Allison
suggests using test strips that measure depletable
Always maintain engine coolant at the proper level. A
inhibitor concentration directly.
Do not use one
low coolant level allows the water pump to mix air with
manufacturer's test strips to measure the chemical
the coolant. Air bubbles in the coolant can "insulate" the
content of another's antifreeze and/or inhibitors. Always
cylinder walls, preventing normal heat transfer. An
follow
the
manufacturer's
recommended
test
abnormally low coolant level can cause the water pump
procedures.
to become (:air-bound," a condition in which it works
feverishly but pumps nothing.
ANTIFREEZE
When freeze protection is required, an antifreeze
Without proper heat transfer, silicone elastomer head-
meeting GM specification 1899M must be used. An
to-block water hole seals can deteriorate and cylinder
inhibitor system is included in this type of antifreeze and
components can expand so that pistons rapidly cut
no additional inhibitors are required on initial fill if a
through the lubricant on the liner walls. Scuffing and
minimum antifreeze concentration of 30% by volume is
piston seizure may follow.
used. Solutions of less than 30% concentration do not
provide sufficient corrosion protection. Concentrations
CAUTION: Use extreme care when
over 67% adversely affect freeze protection and heat
transfer rates (Fig. 2).
removing a radiator pressure-control
cap from an engine. The sudden
Ethylene glycol base antifreeze is recommended for use
release of pressure from a heated
in all Detroit Diesel engines. Methyl alcohol base
cooling system can result in a loss of
antifreeze is not recommended because of its effect on
coolant and possible personal injury
the non-metallic components of the cooling system and
(scalding) from the hot liquid.
because of its low boiling point. Methoxy propanol base
antifreeze is not recommended for use in Detroit Diesel
An engine may contain the correct amount of properly
engines due to the presence of fluoroelastomer seals in
inhibited coolant, but still fail to adequately cool the
the cooling system.
engine. In cases where this occurs, other causes of low
coolant flow, either engine or cooling system related,
Before installing ethylene glycol base antifreeze in a unit
should be investigated.
that has previously operated with methoxy propanol, the
entire cooling system should be drained, flushed with
I. Always use a properly inhibited coolant.
clean water, and examined for rust, scale contaminants,
etc. If deposits are present, the cooling system must be
2. Do not use soluble oil.
chemically cleaned with a commercial grade heavy-duty
descaler.
3. Maintain the prescribed inhibitor strength.
The inhibitors in antifreeze should be replenished at
4. Always follow the manufacturer's recommendations
approximately 500 hour intervals or by test with a non-
on inhibitor usage and handling.
chromate inhibitor system.
Commercially available
inhibitor systems may be used to reinhibit antifreeze
5. If freeze protection is required, use a solution of
solutions.
water and antifreeze meeting GM specification 1899M.
Sealer Additives
6. Reinhibit antifreeze with a recommended non-
Antifreeze with sealer additives is not recommended for
chromate inhibitor system.
use in Detroit Diesel engines due to plugging
possibilities throughout various areas of the cooling
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