Volvo D12, Operator'S Manual

Page: 45 / 214

Cooling System 41
Additives
Additives are part of most antifreeze and
should be tested for and added to all
coolant mixtures using normal antifreeze. If
extended life coolant is used, the additives
are in the product when mixed. Both types
need to have additives added to after a time.
Additives help prevent rust, scale and min-
eral deposits from forming. Additives also
protect metals from corrosion, prevent wa-
ter pump and cylinder liner cavitation and
contain anti-foaming agents. Additives are
depleted during normal engine operation
and need to be replaced. For normal
coolant mixture, this means the addition of
Supplemental Coolant Additives (SCA) at
any time the additive goes below the rec-
ommended level. For extended life coolant
mixture, this means an extender package
added halfway through the coolant lifetime.
Nitrites or nitrite and molybdate additives
protect the cylinder liner from cavitation
erosion. Nitrites deplete over time, creating
the need for SCA’s or extender. Other
coolant additives also deplete and need re-
placement.
A too low concentration of additives in the
coolant will not provide the protection re-
quired by the cooling system. A too high
concentration of additives in the coolant
can cause additives to solidify and drop out
of the solution, depositing inside the cool-
ing system or form a gel in the radiator.
Deposits can be in the form of sludge and
scale. Deposits accumulate on hot engine
surfaces, reducing the effectiveness of the
cooling system or causing water pump
leaks.