with clean oil (the valve piston must slide
(2) A bypass (pressure relief) valve, located
smoothly in the bore of the cylinder
in the oil filter head permits oil to pass
block), and install the regulating valve
directly to the main oil gallery if the oil
filters become clogged, or when in cold
weather the oil is too thick to flow freely
Note. Turn the valve screw into the cylinder block the
through the filters.
sane number of turns that was required for removal.
for removal and disassembly of the oil filters.
(2) Start engine and allow it to reach normal
c. Reassembly and Installation. Refer to figure 3-
Adjust the oil
14 to reassemble and install the oil filters.
pressure regulating valve screw to obtain
oil pressure of 40 to 50 psi at rated engine
3-26. Oil Filter Relief Valve
Each 3,000 hours of operation, remove, clean, and
3-28. Oil Cooler
inspect the parts of the. oil filter relief valve (fig. 3-14).
a. General. The engine oil cooler (fig. 16),
When piston or inside diameter of the sleeve shows
located on the right side of the engine, consists of a
excessive wear, the parts must be replaced.
corrosion resistant cooling core and tank. The water
pump circulates coolant through the cooling core tubes
and the engine oil pressure pump circulates oil through
the tank, around the outside of the tubes of the cooling
a. General. The oil pressure regulating valve is
core, thereby controlling oil temperature.
located in the main oil gallery at the right-front corner of
the cylinder block. The pressure regulating valve
maintains stabilized oil pressure within the lubrication
(1) Drain cooling system.
system. When the oil pressure at the regulating valve
exceeds approximately 55 psi, the valve piston is raised
off the valve piston seat, and the oil is bypassed directly
from the cylinder block to the oil pan. If the lubrication
system is allowed to sludge, the valve may not work
Note. If oil cooler a is badly clogged, a new oil cooler
properly. If the valve sticks in the open position, a sharp
core must be installed.
drop in the engine oil pressure will occur; if the valve
sticks in the closed position, a sharp rise in the engine
oil pressure will occur.
Every 300 hours of operation,
remove and inspect the oil pressure regulating valve.
in reverse order of removal. Use new
Remove pressure regulating valve screw, noting the
gaskets and performed packings.
number of turns required for removal. Withdraw the
(2) Fill cooling system.
valve spring and piston.
(3) Operate the engine and check for oil and
water leaks at the oil cooler connections.
(1) Thoroughly clean the area in the cylinder
Correct any leaks found. Stop engine and
block, lubricate the valve piston
oil as necessary to raise oil level to the
full mark on oil level gage (dipstick).
Check coolant level and add coolant if