Intake And Exhaust Manifold; Camshaft - GMC 1990 Light Truck Repair Manual

6A1-16 2.5 LITER L4 ENGINE

108. Camshaft

Figure 25—Measuring Camshaft Journal Runout
INTAKE AND EXHAUST
MANIFOLDS
Q * Clean
• Old pieces of gasket from the gasket surfaces.
L*
Inspect
Manifolds for cracks, broken flanges, etc.
Gasket surfaces for heavy scratches.
CAMSHAFT
I P Inspect (Figure 5)
Camshaft lobes and journals for scratches, pitting,
scoring, and wear.
Timing gear for damaged or missing teeth.
t j | Measure (Figures 25 through 27)
Tool Required:
J 7872 Dial Indicator (or equivalent)
Camshaft runout. Mount the camshaft between
centers or in V-blocks. Using tool J 7872 (or
equivalent), check the intermediate camshaft
Figure 26—Checking the Camshaft Journals
F-01998
Figure 27—Measuring Camshaft Thrust Plate
journals. If runout exceeds 0.020-inch, the camshaft
is excessively bent and should be replaced, along
with the camshaft bearings.
Camshaft journal out of round. Use a micrometer. If
the journals are more than 0.001-inch out of round,
replace the camshaft.
1 Camshaft journal diameter. Use a micrometer. The
proper diameter is 1.869-inch.
1 Thrust plate (105) to camshaft (108) clearance. This
clearance governs camshaft end play. Use a feeler
gage. The proper clearance is 0.0015-inch to
0.0050-inch. If the clearance is less than 0.0015-inch
replace the spacer ring (106). If the clearance is
more than 0.0050-inch, replace the thrust plate
(105).
❖ Disassemble (Figure 28)
1. Gear (104) from the camshaft.
• Place the camshaft gear in a press. Support
the camshaft gear. DO NOT support the thrust
plate.
Figure 28—Removing the Camshaft Gear
Clearance (Camshaft End Play)