Oil Level Controller; Crankcase Gas Breather - Kohler SFGLD480 Operation & Maintenance Manual

PRODUCT INFORMATION INDEX DATE
Dep. 2
IC-C-D-25-006e B
January 2015
DESCRIPTION OF A CRANKCASE GAS
RECIRCULATION SYSTEM
O&M_2.002211.810_A_10_2016

2.2 Oil level controller.

This is an oil level valve with a float that allows oil to pass into the crankcase and fill it when the level is too low,
allowing the level to rise until it reaches the correct level before it cuts off the oil supply.
When there is gas recirculation from the crankcase to the intake, given that the pressure in the crankcase does
not have to coincide exactly with atmospheric pressure, it is essential to have an effective oil level control
device, and this is achieved with the automatic level control. This level control is connected to engine crankcase
pressure and not to atmospheric pressure, meaning that we obtain a real measurement of the true level of oil in
the crankcase.
When the crankcase pressure does not coincide with the atmospheric pressure, the dipstick will give a false
reading, as when crankcase pressure is negative it will indicate low oil levels and high levels when it is negative.
The dipstick is a valid means of measuring the oil level when crankcase gases exit to the atmosphere, but not
with recirculation.

2.3. Crankcase Gas Breather

The blow-by gases exit the engine through the "crankcase
breather" made of one cylindrical separator filled with wire-
mesh.
The function of the breather is to separate gas-borne oil.
This oil is collected it in the lower portion and oil is fed back
to the crankcase by gravity.
The breather always lies above the oil level of the engine. It
is part of the engine, whether integrated into a blow-by
recirculation system or an open venting system.
The location of the system in the engine depends on the
type of breather and will be such as to prevent or minimise
the entrainment of oil by the blow-by gases.
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