Pontiac Fiero 1988 Service Manual page 294

GENERAL ENGINE MECHANICAL 6A-17
1.
Remove or Disconnect
Camshaft and rear cover (refer to Specific Engine
Section)
Camshaft Bearings
Select the proper pilot, nut and thrust
washer
Assemble bearing puller (Figure 40). Make
sure the puller nut engages a sufficient
number of threads.
Pull out bearings
1- BACK-UP NUT 5-2 PIECE PULLER SCREW
2 - EXPANING C O L L E T 6-PULLING PLATE
3— BEARING 7-THRUST BEARING
4— EXPANDING MANDREL 8-PULLING NUT
G20036-6A
Figure 40 Removing/Installing Camshaft Bearings
(Typical)
Important
• Camshaft bearings must not be reused once
they have been removed.
Clean
Sealing surfaces on the camshaft rear cover and
on the cylnder block
Install or Connect
1. Camshaft bearings
Select front, rear and intermediate camshaft
bearings.
Select the proper pilot, nut and thrust
washer
Assemble installing tool.
Place bearing onto the tool and index the oil
hole(s) of the bearing with the oil passage(s)
in the cylinder block. Pull bearing into place
(Figure 40).
N O T I C E :
Proper alignment of the oil holes is
critical. Restriction of the oil flow will cause severe
engine damage.
Inspect
With a piece of 3/32" brass rod with a 90°
bend at the end, probe the bearing oil holes
and verify that they are properly aligned
(Figure 41).
CHECKING OIL HOLE ALIGNMENT WITH
BRASS ROD. MAKE ROD AS SHOWN USING
3/32" ROD ABOUT 762mm (30") LONG
G20037-6A
Figure 41 Checking Camshaft Bearing Oil Hole
Alignment
2. Camshaft Rear Cover (soft plug)
- Apply a 3mm (1/8") bead of GM 1052366
RTV sealer, Fel Pro-Black RTV, or
equivalent, to the cover before installing.
V A L V E L I F T E R S
Operation
Oil is supplied to the lifter through a hole in the
side of the lifter body, which indexes with a groove and
hole in the lifter plunger. Oil is then metered past the
oil metering valve in the lifter, through the push rods
to the rocker arms. (Figure 42).
When the lifter begins to move up the cam lobe,
the ball check is held against its seat in the plunger by
the ball check spring which traps the oil in the base of
the lifter body below the plunger. The plunger and
lifter body then raise as a unit, pushing up the push rod
to open the valve. The force of the valve spring which
is exerted on the plunger through the rocker arm and
push rod causes a slight amount of leakage between the
plunger and lifter body. This
" l e a k - d o w n "
allows a
slow escape of trapped oil in the base of the lifter body.
As the lifter rolls down the other side of the cam lobe
and reaches the base circle or
" v a l v e c l o s e d "
position, the plunger spring quickly moves the plunger
back (up) to its original position. This movement
causes the ball check to open against the ball spring and
oil from within the plunger is drawn into the base of
the lifter. This restores the lifter to zero lash.
Valve Lifter Diagnosis
1. Momentarily noisy when car is started:
This condition is normal. Oil drains from the
lifters, which are holding the valves open when
the engine is not running. It will take a few