Pontiac Fiero 1988 Service Manual page 290

GENERAL ENGINE MECHANICAL 6A-13
Figure 30 Measuring Connecting Rod Side Clearance
(Double Rod Journal)
jTJ Important
• Inspect the corresponding bearing inserts
for imbedded foreign material and
determine its source.
• If cracks, severe gouges or burned spots are
found, the crankshaft must be replaced.
S l i g h t
roughness may be removed with
fine polishing cloth soaked in clean engine
oil. Burrs may be removed with a fine oil
stone.
Measure
Crankshaft journals. With a micrometer (or dial
indicator in the case of the main bearing journals)
measure taper and run-out. If the readings are
within specifications, note results for later
selection of bearing inserts (refer to Connecting
Rod and Main Bearings). If not within limits, the
journals may be reconditioned by grinding
(except crankshafts with rolled fillets which must
be replaced).
P Y ] Important
m Note the location of main bearing high
spots. If they are not in line, the crankshaft
is bent and must be replaced.
PISTONS, RINGS AND CONNECTING RODS
4-+ Remove or Disconnect
Mark the piston with the number of the cylinder
from which it is being removed.
Mark the connecting rod and the rod cap so that
they can be reassembled correctly.
Turn the crankshaft to bottom dead center.
Clean
• Carbon from the top end of the cylinder
N O T I C E :
If there is a pronounced ridge at the top
of the piston travel, this ridge must be removed
with a ridge reamer before removing piston and
connecting rod assembly.
Do not use force. Avoid breaking piston rings and
damaging the piston.
4. Connecting rod cap
5. Connecting rod and piston assembly. Push out
with a suitable tool.
N O T I C E :
Install thread protectors to avoid
damage to the crankshaft journal (Figure 31).
1-USE ASHORT PIECE OF
3/8" HOSE AS A GUIDE
G20027-6A
Figure 31 Connecting Rod Protectors (Typical)
Piston P i n - P r e s s Fit and Piston Rings
2.
Disassemble
Tool required:
J 24086 Piston Pin Remover/Installer
Piston and connecting rod assembly
C A U T I O N : U s e c a r e w h e n h a n d l i n g
t h e p i s t o n . W o r n p i s t o n r i n g s a r e
s h a r p a n d m a y c a u s e b o d i l y i n j u r y .
Piston rings. Use a suitable tool to expand the
rings. Piston rings must not be reused.
Place the piston and connecting rod assembly
into Fixture J 24086 and press out the piston pin
(Figure 32).
Clean
# Piston, piston pin and connecting rod
- Sludge
Carbon
Piston ring grooves must be cleaned of
carbon to the bare metal.
Varnish from the piston pin by
soaking in carburetor cleaning
solution.
C A U T I O N : A v o i d i n h a l i n g f u m e s or
e x p o s u r e of t h e s k i n t o c a r b u r e t o r
c l e a n i n g f l u i d , a s b o d i l y i n j u r y m a y
r e s u l t .