When the oil pressure exceeds 965 kPa [140 psi] in the
lubricating oil pump, for instance during cold start-up, the
oil pressure in the pump overcomes the limit valve spring
force.
This allows the excess oil to return to the oil pan pre-
venting possible damage to the lubricating system
components.
Lubricating Oil Filter Bypass Valve
Whenever the pressure drop across the lubricating oil
filter exceeds 689 kPa [100 psid], the oil filter bypass
valve opens and allows lubricating oil to bypass the lu-
bricating oil filter.
This condition can occur during cold ambient (cold lu-
bricating oil) engine start ups.
The purpose of the bypass valve is to maintain lubricating
oil flow to the engine and to prevent an oil filter collapse.
Lubricating Oil Cooler Oil Thermostat
Oil flow through the oil cooler is controlled by a temper-
ature sensitive bypass valve (1) in the oil cooler support
(2).
The oil thermostat is either open (retracted) or closed
(extended), depending on the oil temperature.
When the oil temperature out of the lubricating oil pump
is below 110°C [230°F], the bypass valve is in the open
(retracted) position (1).
Lubricating System General Information Section 2 - Lubricating System
N14Page 2-6
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