GMC 1989 Light Duty Truck, Repair Manual, Page: 548 / 998

6A7-12 6.2 LITER DIESEL
L*
M
CYLINDER BORES
Inspect
Cylinder bores for scoring and other damage.
M easure
C ylinder out of round and taper. Refer to GENERAL
ENGINE MECHANICAL (SEC. 6A).
Cylinder Bore Recomditioning
• Refer to GENERAL ENGINE MECHANICAL (SEC.
6A).
PISTON AND CONNECTING
ROD ASSEMBLIES
Refer to GENERAL ENGINE MECHANICAL (SEC. 6A)
and perform the following:
❖
jn p
L 9
*
Disassem ble
Components as required.
Clean
Components as outlined.
Inspect
Components as outlined.
M easure
Piston pin diam eter and pin to connecting rod
bushing.
Piston to bore clearance, and fit pistons as outlined.
Assem ble
Components as outlined.
I?
Im portant
Each connecting rod and bearing cap should
be m arked, beginning at the front of the
engine. Cylinders 1, 3, 5 and 7 are the left
bank and, 2, 4, 6, and 8 are the right bank.
The num bers on the connecting rod and
bearing cap must be on the same side when
installed in the cylinder bore. If a connecting
rod is ever transposed from one block or
c y lin d e r to another, new c o n n e c tin g rod
bearings should be fitted and the connecting
rod should be numbered to correspond with
the new cylinder number.
M easure
Ring end gap and ring clearance.
In s p e c t
Ring fit.
,J T j|
€
L*
❖
INTAKE AND EXHAUST
MANIFOLDS
Clean
Old pieces of gasket from the gasket surfaces.
Soot deposits from the intake manifold.
Inspect
Manifolds for cracks, broken flanges, and gasket
surface damage.
CAMSHAFT
Im portant
Whenever the camshaft needs to be replaced, a
new set of hydraulic lifters must also be installed.
Inspect (Figure 11)
Camshaft lobes and journals for scratches, pitting,
scoring, and wear.
Thrust plate (113) for wear and scoring.
M easure (Figure 16)
Camshaft journals. Use a m icrometer (figure 16).
The proper journal dim ensions are as follows:
— #5 (rear) journal: 50.975-51.025 mm.
— All others: 54.975-55.025 mm.
CAMSHAFT BEARINGS
Inspect
Camshaft bearings for scratches, pits, or loose fit in
th eir bores. Replace the cam shaft bearings if
necessary.
D isassem ble (Figures 17 and 18)
Tools Required:
J 6098-01 Cam shaft Bearing Remover and
Installer