Chevrolet 1980 Light Duty Truck Service Manual page 443

Fig. 6 A 1 -3 9 ~ R e m o v in g Connecting Rod & Piston Assembly
top of the piston.
3. Use a ridge reamer to remove any ridge and/or
deposits from the upper end of the cylinder bore.
4. Turn crankshaft until piston is at top of stroke and
remove cloth and cuttings.
5. Remove connecting rod cap and install Tool J-6305
(11/32") on studs. Push connecting rod and piston assembly
out of top of cylinder block (fig. 6A1-39). It will be
necessary to turn the crankshaft slightly to disconnect some
of the connecting rod and piston assemblies and push them
out of the cylinder.
Disassembly
1. Remove connecting rod bearings from connecting
rods and caps. If bearings are being reused, place them in
a rack so they may be reinstalled in their original positions.
2. Remove piston rings by expanding and sliding them
off the pistons. Tools J-8021 (3-7/8") and J-22249 (3-15/
16") are available for this purpose.
3. Place connecting rod and piston assembly on tool
J-24086-20. Using an arbor press and piston pin remover,
J-24086-8, press the piston pin out of connecting rod and
piston (fig. 6A1-40).
Cleaning and Inspection
Connecting Rods
Wash connecting rods in cleaning solvent and dry with
compressed air.
Check for twisted or bent rods and inspect for nicks
or cracks. Replace connecting rods that are damaged.
Pistons
Clean varnish from piston skirts and pins with a
cleaning solvent. DO NOT WIRE BRUSH ANY PART
OF THE PISTON. Clean the ring grooves with a groove
cleaner and make sure oil ring holes and slots are clean.
FIXTURE &
SUPPORT
ASSEMBLY
J-24086-20
Fig. 6 A 1-40--Removing Piston Pin
Inspect the piston for cracked ring lands, skirts or pin
bosses, wavy or worn ring lands, scuffed or damaged skirts,
eroded areas at top of the piston. Replace pistons that are
damaged or show signs of excessive wear.
Inspect the grooves for nicks or burrs that might cause
the rings to hang up.
Measure piston skirt (across center line of piston pin)
and check clearance.
Piston Pins
The piston pin clearance is designed to maintain
adequate clearance under all engine operating conditions.
Because of this, the piston and piston pin are a matched set
and not serviced separately.
Inspect piston pin bores and piston pins for wear.
Piston pin bores and piston pins must be free of varnish or
scuffing when being measured. The piston pin should be
measured with a micrometer and the piston pin bore should
be measured with a dial bore gage or an inside micrometer.
If clearance is in excess of the .001" wear limit, the piston
and piston pin assembly should be replaced.
ASSEM BLY
1. Lubricate piston pin holes in piston and connecting
rod to facilitate installation of pin.
2. Place connecting rod in piston and hold in place
with piston pin guide and piston pin. Place connecting rod
and piston assembly on fixture and support assembly.
3. Using piston pin installer, J-24086-9, press the
piston pin into the piston and connecting rod (Fig. 6A1-41).
Make sure installer is set properly (see tool instructions).
IN-LINE 6 6A 1-25
PRESS
-PISTON PIN
REMOVER
J-24086-8
LIG H T T R U C K SER V IC E MANUAL