Mack E7, Service Manual

Page: 270 / 303

Page 8-8
200 ENGINE INSTALLATION & TESTING
Restriction Pressure Test
Perform restriction pressure test at maximum,
full-load condition.
A restriction in the internal portion of cooler may
interfere with proper airflow, and can result in
excessively high pyrometer readings. To perform
a restriction pressure test, use the following
procedure:
1. Units are equipped with connections on the
inward sides of inlet and outlet charge cooler
tubes. Remove plugs and install pressure
gauge lines to begin test.
2. Install the appropriate pressure gauge to
inlet and outlet charge air cooler tubes. The
maximum allowable pressure drop across
cooler is 2 psi (13.79 kPa) at full-load
condition.
If using manometers for this test, the difference
between readings should not exceed 4 in-Hg
(13.5 kPa).
3. If pressure drop is higher than specified
amount, remove CMCAC. Flush the inside
to remove any deposits that may be present.
Do not use caustic cleaners. Be extremely
careful when handling cooler so as not to
damage core.
The clamp springs must always be located on
underside of tube to avoid damaging hood when
closed.
4. Reinstall cooler if removed to flush and then
pressure-test CMCAC system.
5. If cooler passes restriction and pressure
tests, remove test equipment, reinstall inlet
and outlet tubes, hoses and clamps or
reinstall plugs, if equipped. Tighten clamps
to 38 lb-in (4.3 N 폷 m).
Core Repair
Certain types of CMCAC core foreign object
impact damage can be field-repaired (depending
on extent of damage). Other types, or more
extensive damage, cannot be field-repaired and
require core replacement.
Determining whether or not core damage is
repairable is a critical first step. Proper diagnosis
can eliminate costly man hours and keep vehicle
downtime to a minimum.
REPAIR PROCEDURES
The following guidelines will help you determine
which areas are repairable or nonrepairable.
To ensure the CMCAC system will function
properly after repair or replacement, a pressure/
leak test is recommended.
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