Pontiac Fiero 1988 Service Manual page 304

2.5L ENGINE 6A1-3
journal. Oil holes at the connecting rod journals are
located so that oil is supplied to give maximum
lubrication just prior to full bearing load.
CRANKSHAFT AND BEARINGS
The crankshaft is cast nodular iron and is
supported by five main bearings. Number five bearing
is the thrust bearing.
Main bearings are lubricated from oil holes
intersecting the main oil gallery, which runs parallel to
the crankshaft bores along the right side of the block.
FORCE BALANCER ASSEMBLY
A force balancer assembly is used on all cars. Two
eccentrically weighted shafts and gears are counter
rotated by a concentric gear on the crankshaft at twice
crankshaft speed. This tends to dampen engine
vibration. The balancer also includes a sump pick-up
screen, a Gerotor-type oil pump and the oil filter. The
oil filter is serviced through an opening in the bottom
of the oil pan.
OIL PUMP
The Gerotor-type oil pump drives off the back
side of one of the balance shafts. Operation is similar
to Gerotor type pumps shown in Section 6A.
ENGINE LUBRICATION
The pump picks up engine oil from the oil pan
sump and pumps it through the full flow oil filter into
an oil passage, which runs along the right side of the
block and intersects the lifter bosses. Oil from this
passage is then routed to the crankshaft main bearings
and camshaft bearings through smaller drilled
passages. Oil is supplied to the rocker arms through
holes in the hydraulic lifters which feed oil up the
tubular push rods to the rocker arms. The oil is
metered by discs under the push rod seat. Valves are
incorporated into the oil system to insure proper flow
of oil. A bypass valve is located at the oil filter
mounting, allowing oil flow in case the filter becomes
plugged or restricted. The pressure regulator valve,
located in the oil pump body, maintains adequate
pressure for the lubrication system and bypasses any
excess back to the suction side of the pump. Many
internal engine parts have no direct oil feed and are
supplied by either gravity or splash from other direct
feed components. Timing gears are lubricated by oil,
which is supplied through a passage from the front of
the camshaft to a calibrated nozzle above the
crankshaft gear, or fed from the cam bearing. Engine
lubrication diagram is shown in Fig. 6. A full flow oil
filter is standard equipment on the engine. All oil from
the pump passes through the filter before going to the
engine oil galleries. In the filter, the oil passes through
a filtering element where dirt and foreign particles are
removed.
S E R V I C E PROCEDURES
ROCKER ARM COVER
Tool required:
1.
2.
3.
4.
5.
6.
7.
J34144 A Rocker Arm Cover
Remover
Remove or Disconnect
Air cleaner.
PCV valve and hose.
Accelerator and TV cables.
EGR valve.
Rocker arm cover bolts.
Wires from spark plugs and clips.
Rocker arm cover using tool J34144-A.
NOTICE:
Do not pry on cover or damage to
sealing surfaces may result.
i f f
Clean
• Sealing surfaces on rocker arm cover and
cylinder head. Use degreaser to dry
surfaces.
Install or Connect
Fig. 8
1 Apply a continuous 3/16" (5 MM) diameter bead
of RTV sealant (No 1052915, or equivalent)
around cylinder head sealant surface inboard at
bolt holes.
NOTICE:
Keep sealant out of the bolt holes to
prevent damage to the cylinder head.
2. Rocker arm cover and retaining bolts - 5 N-m (4
lb. ft.).
3. Spark plug wires and clips.
4. PCV valve and hose.
5. Accelerator and TV cables.
6. EGR valve and gasket.
7. Air cleaner.
I?
Inspect
• For oil leaks.
ROCKER ARMS, PUSH RODS AND GUIDES
1.
2.
3.
4.
Remove or Disconnect
Rocker arm cover.
Rocker arm bolt and ball.
If replacing push rod only, loosen rocker arm bolt
and swing arm clear of push rod.
Rocker arm, push rod and guide.
Important
Store used components in order so they can
be reassembled in the same location.
Push rod guides are different and must be
reassembled in previous location.