TM 5-4310-354-14
b. Cleaning, Inspection, and Repair.
clean water jackets of salt, lime, or sludge by
submerging cylinder head into a tank of heated
cleaning solution.
Circulate the cleaning
NOTE
solution. When clean, remove cylinder head
from tank and dry with compressed air.
Before cleaning the cylinder head
(24), inspect the cylinder head gasket
(7) Inspect for loose or damaged fuel nozzle holder
(25) and cylinder head (24) for
sleeves (46). If necessary, pull out the sleeves
indications of gasket failure and
and press in new ones. To pull the sleeves, it
leaking.
If cylinder head gasket
may be necessary to thread the inner diameter
failure is apparent, make a thorough
to provide a pulling surface.
check
of
contributing
factors.
Detonation (caused by fuel pump
(8) Water-test the cylinder head for cracks and
being improperly timed or excessive
leaks. Check for cracks in the valve and fuel
use of ether for cold starting) will
nozzle holder sleeve areas using magnetic
cause
a
shock
load
in
the
detection.
combustion chamber which will
damage cylinder head gaskets and, if
(9) Clean all carbon from valves using suitable
allowed to continue, may destroy the
scraping or buffing tools.
piston pins and piston rings. Fuel
with a cetane rating too low may also
(10) Clean the valve guides (43). Remove lacquer or
contribute
to
detonation
and
other deposits by running a valve cleaner or wire
corrosion of the gasket and may
brush through the guides. Inspect the valve
eventually cause leaking. Cooling
guides (43) for excessive wear. The exhaust
solutions which are contaminated by
valve guides will usually show the most wear.
corrosive combustion gases leaking
The maximum allowable bore diameter of the
into the cooling system are very
intake valve guides is 0.3780 inch (9.6012 mm).
detrimental to the internal parts of
The maximum allowable bore diameter of the
the entire cooling system.
exhaust valve guide is 0.3790 inch (9.6266 mm).
(1) Remove all carbon from combustion areas using
(See table 5-2.)
a scraper and wire brush.
(11) Inspect the valve seats. If they are pitted, or if
(2) Discard and replace all gaskets.
new valve guides will be installed, the seats
must be refinished.
(3) Clean all parts in accordance with para 5-7. f.
(12) Inspect the valves (40, 41) carefully. If the
(4) Make sure that gasket contact surfaces on the
stems are bent or badly worn or if the valves are
cylinder head, and the cylinder block, are clean,
deeply pitted, the valves must be replaced by
smooth, and flat. Rework contact surfaces, as
new ones. Valves that are only slightly pitted
necessary, to assure that they are free of
can be used by refacing them on a valve
erosion, pits, burrs, scratches, or any other
grinder.
Exhaust valves must have an
defect.
accurately finished 30-degree face angle and
intake valves a 45-degree face angle.
(5) Check out-of-flatness with straight edge and
feeler gauge; maximum allowable is 0.005 inch
(13) If the valve guides (43) are excessively worn
(0.127 mm) on width or length. Out-of-flatness
and require replacing, it must be done before
should vary gradually and uniformly from end to
any refinishing is done on the valve seats. This
end and side to side. Resurface the cylinder
will ensure that the seat being finished is square
head as necessary by light sanding with an
with respect to the new guide. To drive out the
orbital sander.
guides, use a drift with a 5/8-inch (15.875 mm)
diameter and a 3/8-inch (9.525 mm) diameter
(6) Check for free water flow through the cylinder
pilot. Drive in the new guides so that the
head. If restriction is evident, remove plugs (49,
dimension from
50, 51) and fuel nozzle holder sleeves (46);
7-42
