Tools Required
J 8087 Cylinder Bore Gage
Caution: Bodily injury may occur if the cleaning solvent is inhaled or exposed
to the skin.
Important: Measurement of all components should be taken with the components at
room temperature. Do not use a wire brush in order to clean any part of
the piston.
- Clean the piston and connecting rod in solvent.
- Clean the piston ring grooves with a
suitable ring groove cleaning tool.
- Clean the piston oil lubrication holes and slots.
- Inspect the piston for the following:
• | Eroded areas (1) on the top of the piston |
• | Scuffed or damaged skirt (2) |
• | Damage to the pin bore (3) |
• | Cracks in the piston ring lands, the piston skirt, or the pin
bosses |
• | Piston ring grooves for nicks, burrs, or other warpage which may
cause the piston ring to bind |
- Inspect the piston pin for scoring, wear or other damage.
- Measure the piston ring-to-piston ring
groove side clearance.
6.1. | Insert the edge of the piston ring into the piston ring groove. |
6.2. | Roll the piston ring completely around the piston ring groove. |
• | If binding is caused by distorted piston ring groove, replace
the piston. |
• | If binding is caused by a distorted piston ring, replace the piston
ring. |
- Measure the piston ring side clearance
with a feeler gage.
- If the side clearance is too small try another ring set.
- If the proper piston ring-to-piston ring groove clearance cannot
be achieved, replace the piston and pin assembly.
• | Proper ring-to-piston ring groove clearance for the top ring is
0.04-0.086 mm (0.00158-0.00338 in). |
• | Proper ring-to-piston ring groove clearance for the second ring
is 0.04-0.087 mm (0.00158-0.00342 in). |
- Measure the piston pin diameter using
an outside micrometer.
Important: When fitting pistons, consider both the pistons and the cylinder bore
conditions together. Production and service pistons have the same nominal
weight and may be intermixed without affecting engine balance. If
necessary, used pistons may be fitted selectively to any cylinder
of the engine, providing the pistons are in good condition and the
same weight. Do not cut oversize pistons down or the engine balance
may be affected. Finish hone when selecting the piston.
- Measure the piston pin bore using an inside micrometer.
- Subtract the piston pin diameter from the piston pin bore diameter
in order to determine the piston pin-to-piston pin bore clearance.
- Piston-to-piston pin bore clearance must measure 0.0096-0.0215 mm
(0.0004-0.0008 in). Replace the piston and the piston pin if
the piston and the piston pin are not within specifications.
- Measure the piston diameter with a micrometer
at a right angle to the piston bore with the piston pin removed, and
record the measurement. Measure the piston at 49.8 mm (1.9606 in)
from dome of piston. Piston diameter must measure 88.966-88.984 mm
(3.5026-3.5033 in). Replace the piston and the pin as
an assembly if the piston is not within specifications.
- Measure the cylinder bore, using J 8087
.
- Measure the J 8087
.
Record this reading.
- Subtract the diameter of the piston from the diameter of the cylinder
bore to determine the piston-to-bore clearance. The cylinder bore clearance
for pistons 1-4 must be 0.07-0.053 mm (0.0013-0.0027 in),
pistons 5-6 must be -0.008-0.048 mm (-0.0003-0.0018 in).
- If a used piston is not acceptable, inspect the service piston
sizes and determine if a new piston may be selected. Service pistons are
available in standard, and 0.5 mm (0.012 in) oversize.
- When a piston has been selected, mark the piston in order to identify
the cylinder for which the piston was fitted.
- Inspect the connecting rod for an out-of-round
bearing bore. If the out-of-round measurement exceeds 0.005 mm (0.0002 in)
the connecting rod must be replaced.
- Inspect the connecting rod for twisting.
21.1. | Install the connecting rod cap. |
21.2. | Place the connecting rod assembly on a checking fixture. Inspect
the assembly for bending or twisting. |
21.3. | Do not attempt to straighten the connecting rod. |
Ensure that the connecting rod meets the following conditions:
• | The connecting rods are not bent more than 0.18 mm (0.007 in). |
• | The connecting rods are not twisted more than 0.038 mm
(0.0015 in). |
21.4. | Replace any bent or twisted connecting rods. |
21.5. | Inspect the new connecting rods before using the new rods. |
- Inspect the connecting rod for damage to the bearing cap and bolt
threads.
- Measure the piston compression ring end
gap.
| Important: Fit each compression ring to the cylinder in which it will be used.
|
23.1. | Place the compression ring into the cylinder bore. |
23.2. | Push the compression ring into the bottom of the cylinder bore
to approximately 6.5 mm (0.25 in) above ring travel. |
The ring must be square to the cylinder wall.
23.3. | Use a feeler gage in order to measure the end gap. The first compression
ring end gap must measure 0.15-0.36 mm (0.006-0.014 in),
the second compression ring, 0.48-0.74 mm (0.0188-0.0291 in). |
23.4. | Select another size ring set if the end gap exceeds specification.
If ring gap clearance is below specification, increase the gap by carefully
filling off excess material. |
- Inspect the connecting rod bearings
for craters or pockets. Flattened sections on the connecting rod bearing
halves may indicate fatigue.
- Inspect the connecting rod bearings
for excess scoring or discoloration.
- Inspect the connecting rod bearings for dirt or debris imbedded
into the connecting rod bearing halves.
- Inspect the connecting rod bearings
for improper seating indicated by bright, polished sections of the
bearings.
- Inspect the inside of the connecting rod bearing and the outside
diameter fo the connecting rod bearing journal for wear. This indicates
high spots.