TM 5-3895-346-14
ENGINE OVERHAUL
LUBRICATING OIL COOLER
LUBRICATING OIL COOLER
Engine oil coolers are provided for all engines. The oil cooler is mounted on the side of the cylinder block.
To assure engine lubrication should the oil cooler become plugged, a bypass valve located near the top of the
lower engine front cover bypasses oil from the oil pump discharge port directly to the oil galleries in the cylinder
block. The bypass valve opens at approximately 52 psi (359 kPa) (current in-line engines) or 30 psi (207 kPa)
(former in-line engines). The valve components are the same as and serviced in the same manner as the oil
pressure regulator valve in Lubricating Oil Pressure Regulator.
Coolant circulated through the oil cooler completely surrounds the oil cooler core. Therefore, whenever an oil
cooler is assembled, special care must be taken to have the proper gaskets in place and the retaining bolts
tight to assure good sealing.
The oil cooler housing on an in-line engine is attached to an oil cooler adaptor which, in turn, is attached to the
cylinder block. The flow of oil is from the oil pump through a passage in the oil cooler adaptor to the full-flow oil
filter, which is also mounted on the oil cooler adaptor, and then through the oil cooler core and the cylinder
block oil galleries.
Remove Oil Cooler Core
1. Drain the cooling system by opening the draincock at the bottom of the oil cooler housing.
2. Remove any accessories or other equipment necessary to provide access to the cooler.
3. On in-line engines, loosen and slide the clamps and hose back on the water inlet elbow on the cylinder
block.
4. Loosen and slide the clamps and hose back on the tube leading from the thermostat to the water pump.
5. Remove the bolts and lockwashers which attach the water pump to the oil cooler housing.
6. Matchmark the end of the oil cooler housing, cooler core and adaptor with a punch or file so they can be
reinstalled in the same position.
7. Remove the bolts and lockwashers which attach the oil cooler housing to the adaptor or cylinder block and
remove the housing and core as an assembly. Be careful when withdrawing the assembly not to drop or
damage the cooler core.
8. If the adaptor is to be removed, the oil filter must first be removed. Then remove the bolts and lockwashers
which attach the adaptor to the cylinder block. Withdraw the adaptor and gaskets.
9. Remove all traces of gasket material from the cylinder block and the oil cooler components.
Clean Oil Cooler Core
1. Clean oil side of Core - Remove the core from the oil cooler. Circulate a solution of trichloroethylene
through the core passages with a force pump to remove the carbon and sludge.
WARNING
This operation should be done in the open or in a well ventilated room when trichloroethylene or other toxic
chemicals are used for cleaning.
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