TM 5-2410-241-23-1
0006
LUBRICATION SYSTEM CONTINUED
The oil bypass valve is normally closed if the pressure across the engine oil cooler is less than 22 3 psi
(155 21 kPa). This will direct the oil through the engine oil cooler.
Approximately five percent of the oil flow is directed through the orifice of a passage that leads to bypass housing.
The oil flows through the bypass housing and to the engine oil sump. The main oil flow flows toward the engine oil
filter. When the oil pressure differential across oil filter bypass valve reaches 25 psi (172 kPa), the valve allows the
oil to bypass the engine oil filter in order to lubricate the engine parts. The bypass valve provides immediate
lubrication to the engine components when there is a restriction in the engine oil filter due to the following
conditions:
Cold oil with high viscosity
Plugged engine oil filter
Filtered oil flows through the main oil gallery in the cylinder block to the following components:
Piston cooling jets
Valve mechanism
Camshaft bearings
Crankshaft main bearings
Turbocharger
An oil cooling chamber is formed by the following pieces: the lip forge at the top of the skirt of the piston and the
cavity behind the ring grooves in the crown. Oil flow from the piston cooling jet enters the cooling chamber through
a drilled passage in the skirt. The oil returns to the sump through the clearance gap between the crown and the
skirt. Four holes that are drilled in the piston oil ring groove to the interior of the piston drain excess oil from the oil
ring. The breather assembly allows engine blowby to escape from the crankcase. The engine blowby is discharged
into the atmosphere through a hose. This prevents pressure from building up that could cause seals or gaskets to
leak.
END OF WORK PACKAGE
0006-6
