GMC 4000 Series Service Manual page 281

Sec. 6A
Page 270
GASOLINE ENGINES
groove of the stem, making sure the seal is flat
and not twisted.
NOTE: A light coat of oil on the seal will help
prevent twisting.
7. Install the valve locks and release the com­
pressor tool, making sure the locks seat properly
in the upper groove of the valve stem.
NOTE: Grease may be used to hold the locks
in place while releasing the compressor tool.
CYLINDER HEAD ASSEMBLY
REPLACEMENT
REMOVAL
1. Remove manifold assembly.
2. Remove valve mechanism.
3. Drain cooling system .
4. Remove fuel and vacuum line from retain­
ing clip at water outlet, then disconnect wires
from temperature sending units.
5. Disconnect upper radiator hose at water
outlet housing and battery ground strap at cylinder
head.
6. Remove coil.
7. Remove cylinder head bolts, cylinder head
and gasket. Place cylinder head on two blocks of
wood to prevent damage.
INSTALLATION
CAUTION: Gasket surfaces on both
the head and the block must be clean of
any foreign matter and free of nicks or
heavy scratches.
threads in the block and threads on cylin­
der head bolt must be cleaned. (Dirt will
affect bolt torque.) Do NOT use gasket seal­
er on composition steel-asbestos gaskets.
Figure 21 — R e m o vin g O il Seal from
Bearing C a p G roove ITypicalI
G M C S E R V I C E M A N U A L
Cylinder head bolt
1. Place the gasket in position over the dowel
pins with the bead up.
2. Carefully guide cylinder head into place
over dowel pins and gasket.
3. Coat threads of cylinder head bolts with
sealing compound and install finger tight.
4. Tighten cylinder head bolts a little at a
tim e in the sequence shown in figure 13, until the
specified torque is reached (95 foot-pounds).
5. Install coil (if removed).
6. Connect upper radiator hose and engine
ground strap.
7. Connect temperature sending unit wires
and install fuel and vacuum lines in clip at water
outlet.
8. Fill cooling system .
9. Install manifold assembly.
10. Install and adjust valve mechanism as
previously instructed.
Do install rocker arm cover.
NOTE: NOT
11. Start engine and allow to warm up, re­
torque cylinder head and readjust valves.
NOTE: Use of commercially available oil de­
flector clips (14) on rocker arms will prevent oil
spatter during warm-up.
12. After making foregoing adjustment install
rocker arm cover using new gasket. Install air
cleaner and connect manifold heat stove pipe.
OIL PAN REPLACEMENT
OIL PAN REMOVAL
1. Clean all dirt and accumulated material
from oil pan attaching bolts and drain plug.
2. Drain oil out of crankcase.
3. Remove oil pan bolts, then remove oil pan.
Scrape off any portions of gaskets which adhere to
oil pan flange or bolting flange on engine block and
front cover. Gasket at front cover is neoprene type.
Remove seal at crankshaft rear bearing cap.
INSTALLATION
1. Install seal at rear bearing cap.
2. Install front seal on timing gear cover,
pressing tips into holes in cover.
3. Use grease or cement to hold side gaskets
in place on cylinder block. Side gasket tabs must
index with front seal on timing gear cover.
4. Install oil pan.
OIL PUMP REPLACEMENT
REMOVAL
1. Remove oil pan as previously directed under
appropriate heading.
2. Remove bolt attaching oil suction pipe. Re­
move two bolts holding pump flange to engine, then
remove pump and screen as an assembly.