GMC C Series 1993, Repair Manual

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6A2-24 y a ENGINES, GASOLINE
2. Caps (253), shields (255), springs with dampers
. (256) and rotators (254).
3; O-ring Seals (252) Or seals (257).
4, Valves (258 and 259). Place them |n a rack so they
can be returned to their Original position at assenv
b ly .: \ .. ;;
• Valve guides using J 8101 (figure 48).
• Valve stems and heads on a wire wheel.
• Carbon and old gasket from the cylinder head gas­
ket surface.
| y | Inspect (Figure 45) *
CLEANING AND INSPECTION
s Clean (Figures 47 and 48)
Tools Required:
J 8089 Wire Brush (or equivalent).
J 8101 Valve Guide Cleaning Tool
• Carbon from the combustion chambers using
J 8Q59 (or equivalent) (figure 47). 1
B4519
Figure 47—Cleaning the Combustion Chambers
• Cylinder head for cracks in the exhaust ports, com­
bustion chambers, or external cracks to the coolant
jackets. Gasket surfaces should be free of damage.
• Valves for burning, pitting, or warpage. Grind or
replace as needed as outlined later. Check the
valve stems for scoring or excessive wear. Stems
must not be bent.
• Valve seats for pitting or other damage. Grind or
reface as needed.
• Rotators, th e rotators should rotate smoothly, with­
out binding.
Measure (Figures 49 through 51)
Tools Required:
J 8001-M Dial Indicator (or equivalent)
J 9666 Valve Spring Tester (or equivalent)
Figure 50— Measuring Valve Spring Tension