Chevrolet 1988 Light Duty Truck Repair Manual page 337

Figure 8— Measuring Piston Pin Diameter
CLEANING AND INSPECTION
Clean
Piston.
— Remove all varnish and carbon deposits. DO
NOT USE A WIRE BRUSH.
— Remove the carbon from the ring grooves. Use
a ring groove cleaning tool.
— Oil control ring groove holes.
I9
Inspect
Piston pin bore in the piston and connecting rod.
Check for scuffing, burrs, etc.
Piston for scratches, wear, etc.
Connecting rod for cranks, nicks, etc. If a suitable jig
is available, check the connecting rod for a bent or
twisted condition.
Piston.
— Ring land for cracking, wear, etc.
— Ring grooves for burrs, nicks, etc.
— Skirts and pin bosses for cracking.
— Skirts for scuffing.
Connecting rod bearing inserts for scratches or
deep pitting.
MEASURING PISTON PIN TO PISTON
CLEARANCE (ALL EXCEPT 6.2 L)
M easu re (F ig u res 8 and 9)
1. P iston pin d ia m e te r (fig u re 8). C h e ck a g a in st
" S pecifications."
2. Piston pin to piston clearance.
• Measure the piston pin hole diam eter (figure
9).
• S ubtract the piston pin d iam eter from the
p is to n p in h o le d ia m e te r to o b ta in th e
clearance.
• R eplace the piston and piston pin if the
clearance exceeds specifications. The piston
and piston pin are a matched set and are not
available separately.
MEASURING PISTON PIN TO PISTON
PIN BUSHING CLEARANCE (6.2 L ENGINES)
^2® C lean
• Piston pin and bushing. The parts must be free of oil
and dirt.
GENERAL ENGINE MECHANICAL
B-04981
Figure 9— Piston Pin Hole Diam eter
M easu re (F ig u re s 8 and 10)
P iston pin d ia m e te r (fig u re 8). C h eck a g a in s t
" S pecifications."
Piston pin bushing ID. Use an inside microm eter
(figure 10).
3. Piston pin to bushing clearance. Subtract the piston
pin d ia m e te r from the piston
Compare with " S pecifications."
excessive, try a new piston Din.
Figure 10— -Measuring Piston Pin Bushing Inside
6A-7
-04980
pin b u sh in g ID.
If the clearance is
If the clearance is
B-04985
Diameter