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 TM 55-1905-223-24-1
CAUTION
If magnetic crack detector is used, the head must be
demagnetized and cleaned thoroughly. Powdered fragments
can damage the internal engine components.
(b) Magnetic crack detector.
1
Remove keeper bar from magnet poles and place magnet on area to be inspected.
2
Spray powder on area to be inspected with powder bulb. Remove excess powder with low
pressure
air.
3
Inspect for cracks. Cracks will show as white lines.
CAUTION
Both ends of a crack between the valves must be visible. If one
end of a crack extends into the valve seat insert bore behind the
valve seat insert, the condition of the cylinder head is
questionable. To be sure the cylinder head is in good condition,
remove the valve and the valve seat insert.
(15)
Inspect for cracks on the combustion surface (FIG. 4-1). If any cracks around the injector
bore are longer than 0.25 inch (6 mm) discard the cylinder head.
CAUTION
The upper (rocker lever housing) surface and the lower (cylinder
block) surface of the cylinder head must be parallel within 0.005
inch (0.13 mm). If these surfaces are not square, the cylinder
liner bore can be distorted.
NOTES
The head can be resurfaced as long as the thickness (1, FIG. 4-
9) is at least 4.715 inch (119.76 mm) after the head is
resurfaced.
If the head is resurfaced, be sure that the injector protrusion and
the valve depth in the head are adjusted properly.
(16)
Use a straight edge and a feeler gauge to measure the flatness of the head gasket surface
mm) will fit between the straight edge and the cylinder head.
(17)
Check the valve guides (7, FIG. 4-3) for chips or cracks. Replace the guide if it is
chipped or cracked.
4-12
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