TRUCK SERVICE MANUAL
ENGINE
CAUTION
INSTRUCTIONS FOR USE OF SERVICE TOOLS
Never vacuum test cylinder head with injectors installed.
ST-981 Injector Tip Protrusion Checking Tool
Installation of injectors while head is removed from block
To check injector tip protrusion with injector sleeves
could cause misalignment of valves in valve seat area
installed:
and result in leakage during testing which would not
Note: The cylinder head must be on a flat metal surface,
necessarily occur during actual engine operation.
valves removed for this measurement. If tip protrusion
1. Operate vacuum pump until hand on vacuum
exceeds specifications injector sleeves must be
gauge (1, Fig. 2-13) reaches 18 to 25 inches vacuum.
replaced.
Close shut-off valve (2), release push-button to stop
1. Loosen indicator clamping screw and raise
pump.
indicator. Push plunger end down, against a flat metal
2. Time fall of gauge hand as follows: a. Begin
surface, until plunger is fully compressed.
timing as soon as hand reaches "18" on dial.
2. Lower dial indicator until maximum reading is
b. Stop timing when hand reaches "8." c. If
obtained, plunger bottoms and hand movement stops,
elapsed time is less than ten seconds, valve seat is
then back off 0.010 inch as indicated by hand movement;
unsatisfactory.
tighten indicator clamping screw.
3. Tap stem end of valve with a soft-faced mallet
3. Push plunger against a flat metal surface until
and retest. If valve seat is unsatisfactory:
plunger is fully depressed, set indicator at 0.076 inch
a. Check for leaking connections in tester; operate
reading on dial.
vacuum pump against a clean window glass or any
4. Position tool into injector sleeve bore, with tool
smooth flat surface; fall of indicator hand indicates a
firmly seated, indicator should read "O" +0.0025 inch to
loose connection.
provide 0.060 to 0.070 inch injector tip protrusion. The
b. Check valve and seat face area to be sure they
indicator plunger drops 0.176 inch (dial makes one (1)
are free of dirt particles.
complete revolution) below tip of gauge.
4. Regrind seat and reface valve if necessary;
To check injector tip protrusion with injector sleeves
however, it is possible to mistake leakage around valve
removed:
seat insert for valve seat leakage. If this type leakage is
1. Follow Steps 1, 2 and 3 preceding.
suspected, apply
2. Place tool on beaded seat of injector sleeve
bore. The indicator should read "O" + 0.005 inch for the
correct depth of seat bore. The indicator plunger on this
measurement drops approximately 0.076 inch below tip
of gauge.
ST-1244
Injector Sleeve Puller/ST-1247
Impact
Socket Wrench
Remove injector sleeves marked for replacement as
follows:
1. Position ST-1244 Injector Sleeve Puller into
injector bore; allow forming collar teeth to rest on injector
1. Vacuum Gauge
sleeve. Back nuts off to extent of their threads.
2. Shut-off Valve
2. Place driving buffer over tool, drive complete unit
Fig. 2-13 (N10283) Vacuum test valves for leaks
down until forming collar bottoms. Remove driving buffer
grease around outside edge of insert to make a grease
and tighten top nut until snug.
seal.
3. Place ST-1247 Impact Socket Wrench over
5. Perform vacuum test and inspect grease seal for
lower nut. Using impact wrench or ratchet run nut down
a break indicating air leakage between wall of
until injector sleeve is free.
counterbore and valve seat insert. If leak around valve
4. Firmly hold puller, back off lower nut. Remove
seat insert is found:
socket. Back top nut off to extent of threads.
a. Stake or peen insert, vacuum test.
b. Remove insert, counterbore for next smallest
oversize. See "Replace Valve Seat Insert."
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