Discharge Valve, Valve Stop, And Seat - GMC C Series 1993 Repair Manual

Tighten
RS
Bolts to 15 N-m (11 ft. lbs.).
Important
• Do not move the connecting rod or crankcase, or a
false reading may be obtained.
D. Check the measurement bn the gaging material
scale (figure 22).
E. Replace the connecting rod if the clearance is
excessive or if the bearings are cracked or
flaked.
F. Position the cap to locate the locking slots next
to the same bolt.
8. Piston and piston ring.
• Replace any piston that is scored, cracked, or
has enlarged ring grooves.
• Measure each piston with a micrometer in rela­
tion to the cylinder bore diameter. Maintain a
0.0128 to 0.0177-inch clearance between the
cylinder wali and the piston (figure 23).
• Check the fit of the piston pins to the pistons
and connecting rod bushings, Refer to "Specifi­
cations" for clearance. If the fit is loose, replace
the piston and pin assembly.
• Check the fit of the piston pin in the connecting
rod bushing by rocking the piston. If clearance
is found, replace the rod and bushing assembly.
• Check the fit of the piston rings in the piston
ring grooves (figure 25). Refer to "Specifica­
tions" for clearances.
REPAIR

DISCHARGE VALVE, VALVE STOP, AND SEAT

Lap slightly worn discharge valve seats with a lapping
stone or grinding compound and grinding tool.
install new valve springs, valves, and screw-in dis­
charge valve seats. Make sure that measured dis­
charge valve travel does not exceed 0.032 inch.
To test for leakage, apply a water and soap solution
and 338 kPa (100 psi) of air to the cylinder head dis­
charge valve and seats. Leakage in the form of soap
bubbles is permissible.
Figure 23— Measuring the Piston Diameter
AIR COMPRESSOR AND GOVERNOR 5J-13
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