Oil Pump Installation; Oil Pan Installation; Cylinder Head Installation - GMC 1990 Light Truck Repair Manual

Locate the piston ring end gaps as shown in
figure 33. Lubricate the piston and rings with
engine oil.
Without disturbing the ring end gap location,
install J 8037 over the piston (figure 34).
The piston must be installed so that the notch
in the piston faces the front of the engine
(figure 33).
Place the piston in its matching bore. The
connecting rod bearing tang slots must be on
the side opposite the camshaft. Using light
blows with a hammer handle, tap the piston
down into its bore (figure 34). At the same
time, from beneath the vehicle guide the
connecting rod to the crankpin with J 5239
(figure 35). Hold the ring compressor against
the block until all rings have entered the
cylinder bore.
Remove J 5239 from the connecting rod bolts.
Important
• Each connecting rod and bearing cap should
be marked, beginning at the front of the
engine. Cylinders 1, 3 and 5 are at the left
bank and 2, 4 and 6 are the right bank. The
numbers 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 cylinder to
another, new connecting rod bearings should
be fitted and the connecting rod should be
numbered to correspond with the new cylinder
number.
3. Connecting rod cap with bearing insert.
Measure
Connecting rod bearing clearance. Refer to
GENERAL ENGINE MECHANICAL (SEC. 6A).
Tighten
S t
Connecting rod cap nuts to 60 N m (45 ft. lbs.).
Measure
Connecting rod side clearance (figure 36). The
proper clearance is 0.006 to 0.014-inch.

OIL PUMP INSTALLATION

Install or Connect
1. Oil pump to the engine.
• Align the slot in the oil pump shaft with the
tang on the distributor shaft.
• The oil pump should slide easily into place.
• No gasket is used.
2. Oil pump to main bearing cap bolt.
Tighten
Oil pump to main bearing cap bolt to 90 N m
(65 ft. lbs.).
4.3 LITER V-6 6A3-21

OIL PAN INSTALLATION

-► «- Install or Connect (Figure 37)
Apply PST sealant (GM part number 1052080 or
equivalent) to the front cover to block joint and to the
rear crankshaft retainer seal to block joint. Apply the
sealant about 25 mm (1-inch) in both directions from
each of the four corners (figure 37).
Oil pan gasket to the oil pan.
Oil pan to the engine.
Oil pan reinforcements, bolts and nuts.
Tighten
• Bolts to 11.3 N m (100 in. lbs.).
• Nuts to 22.6 N m (200 in. lbs.).

CYLINDER HEAD INSTALLATION

& 5 J ® Clean
• Gasket surfaces on the block and cylinder head.
-► <- Install or Connect (Figure 38)
1
Head gasket.
.
• If a steel gasket is used, coat both sides of the
gasket with sealer. Spread the sealer thin and
even.
• Do not use
steel-asbestos gaskets.
• Place the gasket over the block dowel pins
with the head up.
Cylinder head. Carefully guide the cylinder head
2
.
into place over the dowel pins and gasket.
Cylinder head bolts. Coat threads of the cylinder
3.
head bolts with sealing compound (GM part number
1052080 or equivalent) and install finger-tight.
Tighten
Cylinder head bolts, a little at a time, using the
sequence shown in figure 38. The proper
torque is 90 N m (65 ft. lbs.).
sealer on com po sition