ACtion Magazine - March 2017 - 30

What you don't know can hurt your diesel engine

Common failures
Using the right coolant is important to preventing
heavy-duty engine failures. Let's walk through some of
the most common:
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Liner pitting: You'll see pitting most frequently
on the side of the liner where the piston strikes just after
the cylinder fires, and to a lesser degree on the opposite
side where the cylinder strikes on the up-stroke. However,
this type of damage can show up anywhere the level of
vibration is high. Because of variations from cylinder to
cylinder and engine to engine, no two liners will appear
the same.
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Additive Dropout: When additives become unstable they can leave the coolant system unprotected against
corrosion. Dropout can happen for several reasons, including coolant contamination, over-treatment of SCAs, and
an improper mix of water, glycol, and inhibitors. Some
additives will collect in the cool areas of the engine when
instability occurs and impede heat transfer.
To reduce the risk of dropout, make sure the water used
for mixing coolant is of good quality; most tap water is
hard and can react with additives, causing them to become
insoluble. When adding SCAs or extenders, more is not

always better. If the additive concentration gets too high,
the coolant will not be able to hold all of the additives in
solution.
*
Water Pump Failure: Hard water and additive
dropout can lead to deposits on water pump face seals. So
can particulate left by the manufacturing process of engine
hardware.
Filtering these contaminants will not only reduce water
pump failure, it can guard against engine wear, radiator
failure, overheating, thermostat failure, and other coolant
system component problems.
Water filters containing SCAs are a reliable way to
meter out supplemental additives and coolant extenders
during a service interval. For coolant systems above 20
gallons (76 liters), or if a liquid extender or SCA is used
instead of a filter to replenish the SCA, use a blank water filter. For OAT coolants, blank water filters should be
used.
*
Corrosion: Historically, heavy-duty engines used
a lot of cast iron and copper. But more heavy-duty coolant
systems are incorporating aluminum radiators and oil coolers. The manufacturing process for these components uses
a residual brazing compound that can partially dissolve
into the coolant and introduce contamination. Some of the
additives in conventional and hybrid coolants can have an
adverse reaction in environments with brazing compound
contamination and aggravate aluminum corrosion. When
corrosion begins to occur, the aluminum is weakened and
is prone to stress fractures.
OAT coolants are typically more robust for protecting
against this type of contamination in the cooling system.
It's estimated that 40% of all engine problems originate
in the cooling system, meaning that selecting and maintaining your coolant is critical to protecting your equipment. When in doubt, follow the engine manufacturer's
recommendations for coolant type and service intervals. ❆
Lauren Lewis is Product Development Engineer,
Coolants & Chemicals, at Cummins Filtration. She
has a BS in Chemistry from Tennessee Tech University.

ACTION * March 2017

http://www.johnsonmfg.com/

Table of Contents for the Digital Edition of ACtion Magazine - March 2017