Camshaft - GMC T Series 1994 Repair Manual

Flanges
the same side when installed in the cylinder
bore. If a connecting rod is ever transposed
from one block or cylinder to another, new con­
necting rod bearings should be fitted and the
connecting rod should be numbered to corre­
spond with the new cylinder number. On 7.4L
engines the rod is not symmetrical and the out­
side always faces out.
Measure
m
Ring end gap and ring clearance. Refer to Section
6
A.
Inspect
1?
• Ring fit. Refer to Section
INTAKE AND EXHAUST
MANIFOLD
IJ ji Clean
• Old pieces of gasket from the gasket surfaces.
• Excessive carbon build-up in the exhaust passages
of the intake manifold.
• Scale and deposits from the coolant passages of
the intake manifold.
• EGR passage (if used) of excessive carbon depos­
its.
L*
Inspect (Figure 44)
• Manifolds for cracks, broken flanges, and gasket
surface damage.
• A lignm ent of exhaust manifold flanges. Use a
straight edge and feeler gage (figure 44). If the
flanges do not align, the manifold is warped and
should be replaced or resurfaced.
• AIR system injection tubes for damage. Replace as
needed.
6
A.

CAMSHAFT

Important
• Whenever the camshaft needs to be replaced, a
new set of valve lifters must also be installed.
Inspect
L *
Camshaft lobes and journals for scratches, pitting,
scoring, and wear.
Measure (Figures 45 and 46)
Tool Required:
J 7872 Dial Indicator (or equivalent)
Camshaft runout (figure 45). Mount the camshaft in
V-blocks or between centers. Using J 7872, check
the intermediate camshaft journal. If runout on
5.0/5.7L engines exceeds 0.0254 mm (0.002 inch)
and on 7.4L engines 0.0635 mm (0.0025 inch), the
cam shaft is excessively bent and should be
replaced along with the camshaft bearings.
Camshaft journal out-of-round. Use a micrometer
(figure 46). If the journals are more than 0.00254
0.001
mm ( inch) out-of-round, replace the cam­
shaft.