TRUCK SERVICE MANUAL
using ST-1166 Magnetic Crack Detector in valve and
injector port areas. Discard head if cracked.
1. Check for loose valve seat. inserts by lightly
tapping cylinder head near insert, if valve seat is loose
enough to bounce, mark for replacement. A slight
looseness found only by tapping when head is cold and
covered with a film of oil is not objectionable.
2. If seat area width (2, Fig. 2-4) exceeds 0.125
inch [3.18 mm] at any point and cannot be narrowed
sufficiently (1) during regrind, mark for replacement.
Fig. 2-3 (V10244) Cylinder head installed In ST-1012
may not show water leakage. Discard head if cracked;
replace leaking sleeves.
2, Open water outlet of test fixture; check for free water
circulation through cylinder head. If restriction is evident,
remove all pipe plugs and fuse plug; clean water jackets
of salt, lime or sludge.
a. If alkaline cleaners are used in recommended
concentration, immersion times are followed and
temperatures regulated according to instructions
supplied with each product, no damage will result to
injector sleeve "0" rings.
Fig. 2-4 (N10228) Valve seat insert-cross section
b. Solvent type cleaners may damage the "O" ring
and should not be used unless the injector sleeves and
"0" rings are all to be replaced.
Note results of pressure test. Leaks indicate need for
replacement of injector sleeves. Visually check sleeves,
c. To remove heavy deposits of lime, use circulated
which pass pressure test, for scratches on cup seat
area. If seat area is scratched, mark for replacement.
Injector Tip Protrusion
The use of acid is extremely dangerous to workmen and
injurious to machinery. Always provide a tank of strong
Injector sleeves that have passed the above tests must
soda water as a neutralizing agent.
further be checked for injector tip protrusion (seat depth)
and seating pattern.
3. Clean fuel passage with ST-876 Brush or
equivalent. Flush passages with solvent to remove
1. Lightly coat injector cup with Prussian Blue,
install injector assembly into sleeve torque to 10 to 12 ft-
lbs [1.4 to 1.7 kg m]. Remove and check seat pattern.
Magnetic Crack Detection
Bluing band must be 0.060 inch [1.52 mm] minimum in
As a precautionary measure, check cylinder head for
width and located approximately 15/32 inch [11.91 mm]