
HOW-TO SECTION
Dropout
Excessive amounts of some inhibitors
in the coolant can cause a gel or
crystalline deposit that reduces heat
transfer and coolant flow. The deposit,
called “dropout,” takes the color of
the coolant when wet, but appears as a
whiteorgraypowderwhendry.Itcan
pick up solid particles in the coolant
and become gritty, causing excessive
wear of water pump seals and other
cooling system components.
PERSONAL INJURY
To avoid injury when using
caustic cleaning agents, follo w
the chemical manufacturers
usage, disposal, and safety
instructions.
The wet gel can be rem oved by using
a non-acid (alkali) type heavy-duty
cleaner, such as Detroit Diesel Power
Cool On-Line Cleaner (sodium
nitrite/sodium te traborate). Part
numbers are listed in Table 37.
NOTE:
If the gel is allowed to dry, it is
necessary to disassemble the
engine and clean it with a caustic
solution or physically clean individual
components.
Coolant Extender Inhibitor
Additive for “OAT” Coolant
The inhibitors in OAT coolant must
also be maintained, but less of ten
than traditional SCA-type coolants.
A por table test is available to test the
levels of OAT inhibitors in coolant.
Wherethisisnotused,fleet testing
has determined that a OAT coolant
extender packag e should be added to
the coolant a t 300,000 miles (480,000
km), two (2) years, or 5,000 hours,
whichever comes first. The proper
maintenance dosages for all OAT
coolants are listed in Table 21 ,
reflecting 0.6% b y volume extender.
This dosage should be added to the
water-only an d the gly col systems at
the same interval.
The proper application of extender to
OAT coolant will provide:
□ pH Control
□ Restored inhibitor levels to prevent
corrosion
□ Cavitation protectio n t o protect
wet sleeve cylinder liners
NOTE:
Do not use traditional SCAs in
OAT c oolant, and do not use
OAT extender in traditional coolant.
102 All information subject to change without notice. (Rev. 06/06)
DDC-SVC-MAN-0039 Copyright © 2006 DETROIT DIESEL CORPORATION
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