Volvo Penta 300 Series, Руководство по ремонту

Страница: 63 / 96

61
Piston and connecting rod,
inspection
Checking piston wear
Check pistons for cracks, broken piston ring carriers
or worn piston ring grooves. If the piston has deep
scores in the outer mantle the piston (liner kit) must
be discarded. Also if the piston has one or more
cracks in the gudgeon pin hole or combustion cham-
ber bottom. Cracks in the edge of the piston head
around the combustion chamber are generally not
dangerous. The crack test is carried out using the
calcium powder test. If this damage is found the in-
jector equipment should also be checked.
Check gudgeon pin bushing wear. There should not
be any noticeable wear.
When cold the gudgeon pin should have play of be-
tween 0.008–0.018 mm.
If correctly aligned a lubricated gudgeon pin should
be able to slide through the bushing under its own
weight ( at room temperature).
NOTE! The cylinder liner wear should be checked
before replacing piston rings and connecting rod
bushings. See “Cylinder liner, inspection and mea-
surement”.
There are two types of con rods. Late-model con rods
have a trapezoidal gudgeon pin end. Both types can
be mixed during engine renovation, however.
Before the gudgeon pin bush is changed, check the
con rod for cracking, straightness and twist. A
cracked, bent or twisted con rod must be scrapped.
NOTE! Gudgeon pin bushes may only be changed on
early model con rods. On late model con rods (with
trapezoidal gudgeon pin ends), no changes may be
done.
1
Remove the gudgeon pin snap ring and press out the
gudgeon pin with a suitable drift.
2
Use a new piston bolt and measure the connecting
rod in a fixture. The connecting rod is permitted the
following deviation:
A. Out-of-true: Maximum 0.05 mm per 100 mm
measured.
B. Distortion: Maximum 0.1 mm per 100 mm
measured.
Repair Instructions