TM 5-3895-346-14
LUBRICATING OIL COOLER
ENGINE OVERHAUL
Clean the core before the sludge hardens. If the oil passages are badly clogged, circulate an Oakite or alkaline
solution through the core and flush thoroughly with clean, hot water.
2. Clean water side of Cooler - After cleaning the oil side of the core, immerse it in the following solution: Add
one-half pound of oxalic acid to each two and one-half gallons of solution composed of one-third muriatic acid
and two-thirds water. The cleaning action is evidenced by bubbling and foaming. Watch the process carefully
and, when bubbling stops (this usually takes from 30 to 60 seconds), remove the core from the cleaning
solution and thoroughly flush it with clean, hot water. After cleaning, dip the core in light oil.
CAUTION
Do not attempt to clean an oil cooler core when an engine failure
occurs in which metal particles from worn or broken parts are
released into the lubricating oil. Replace the oil cooler core.
Pressure Check Oil Cooler Core
After the oil cooler core has been cleaned, check for leaks as follows:
1. Make a suitable plate and attach it to the flanged side of the cooler core. Use a gasket made from rubber to
assure a tight seal. Drill and tap the plate to permit an air hose fitting to be attached at the inlet side of the core
(Fig. 1).
2. Attach an air hose, apply approximately 75-150 psi (517-1034 kPa) air pressure and submerge the oil cooler
core and plate assembly in a container of water heated to 180
F
Figure 1. Preparing Oil Cooler Core for Pressure Test
(82 ). Any leaks will be indicated by air bubbles in the water. If leaks are indicated, replace the core.
C
WARNING
When making this pressure test, be sure that personnel are
adequately protected against any stream of pressurized water
from a leak or rupture of a fitting, hose, or the oil cooler core.
3. After the pressure check is completed, remove the plate and air hose from the cooler core, then dry the core
with compressed air.
CAUTION
Where a leaking oil cooler core has caused contamination of the
engine, the engine must be immediately flushed to prevent
serious damage (refer to Cooling System).
Install Oil Cooler Core
1. If the oil cooler adaptor (in-line engines) was removed from the cylinder block, remove the old gasket
material from the bosses where the adaptor sets against the block. Affix new adaptor gaskets (Fig. 2), then
secure the adaptor to the cylinder block with five bolts and lockwashers.
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