Section 05: COOLING SYSTEM
PA1562
10
CAUTION
Always test the solution before adding water
or antifreeze.
8. If cooling system is not at the proper
protection level. Mix coolant/water solution to
the proper concentration before adding to the
cooling system
9. Use only non-chromate inhibitors.
10. Distilled water is recommended.
5.5.1 Coolant Not Recommended
• All antifreeze and coolant containing
phosphorous;
• Automotive type coolants;
• Methoxy propanol-base antifreeze;
• Methyl alcohol-base antifreeze;
• Sealer additives or antifreezes containing
sealer additives.
5.5.2 Inhibitors
A coolant solution, which has insufficient
inhibitors or no inhibitors at all, invites the
formation of rust, scale, sludge and mineral
deposits within the cooling system. These
deposits can cause water pump seal wear and
coat the interior of coolant system passages.
Heat transfer is reduced as deposits build up,
leading to an overheating condition. Continued
operation with this condition can lead to serious
engine damage: liner scuffing, scoring, piston
seizure and cylinder head cracking. These
damages can occur quickly or over a longer
period of time, depending of location and
amount of deposits. Improperly inhibited
coolants can become corrosive enough to "eat
away" coolant passages and seal ring grooves
and cause leaks to develop. Hydrostatic lock
can occur if leak is internal and accumulates on
top of a piston. The result may be a bent
connecting rod. Cavitation erosion may occur in
improperly inhibited coolants. Cavitation erosion
is caused by the implosion of tiny bubbles
against localized surfaces of the system. Such
implosion causes pinpoint pressures high
enough to erode pump impellers, cylinder liners
and cylinder blocks. In extreme cases, their
surfaces are so deeply pitted that they appear to
be spongy, and holes can develop completely
through them.
5.5.3 Inhibitor Test Procedures
Test Kits are commercially available to check
engine coolant for nitrite concentration. Nitrite
concentration is an indication of Supplemental
Coolant Additive (SCA) level. Nitrite must be
maintained within recommended levels. Coolant
must be tested at each oil change to insure that
inhibitor levels are maintained within the ranges
shown hereafter:
DDC Fully Formulated Glycol Coolant Limits
-30 -– 50(°F) Freeze Point (°F)
125 -– 500 ppm Boron (ppm)
800 -– 3200 ppm Nitrite (ppm)
200 -– 750 ppm Nitrate (ppm)
50 –- 250 ppm Silicon (ppm)
0 ppm MAX Phosphorus (ppm)
8.0 -– 11.0 pH
40 ppm MAX Chlorides (ppm)
100 ppm MAX Sulfates (ppm)
NOTE
Above SCA values with Detroit Diesel #7se298
or TMC RP-329 “Type A”. Use Nalco Chemical
Company nitrite test kits (CO-318). A factory
coolant analysis program is available through
Detroit Diesel distributors under part number
23508774.
5.5.4 Additives Not Recommended
• Soluble Oils;
• Chromates.
WARNING
Never remove filler cap while coolant is hot.
When coolant is at ambient temperature,
release pressure from system by turning the
pressure cap counterclockwise 1/4 turn; then
remove filler cap slowly. A sudden release of
pressure from the heated cooling system can
result in severe burns from the expulsion of
hot coolant fluid.
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