Lister Petter 0600123LPW3A01, Руководство по ремонту, Страница: 39 / 88

ALPHA series engines worksHoP mAnuAL
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2.33.4 inspecting and servicing the Piston
1. Thoroughly clean the cylinder barrel and check
for scoring and wear.
2. Clean the piston, removing all traces of carbon
from both the upper and underside of the crown
and the ring grooves.
3. With the piston rings in an unworn section of the
cylinder barrel check for the correct gap clearance;
refer to " 5.7.4 Dimensions of Wearing Parts".
4. Clean the connecting rod.
5. Examine the small end bush for wear.
6. If the big end has been dismantled because of
metal failure, the oil passages in the crankshaft
must also be examined for obstruction and
fragments of metal.
2.33.5 fitting a Piston
The pistons with rings and connecting rods
assembled, must be submerged in oil just before
fitting into the cylinder. After submersion drain
both ways so that no oil is left in the combustion
chamber or inside the piston.
CAution
Ensure the correct type of piston for the engine
is being replaced.
Figure 2.33.5 Piston
A - LPW; B - LPWS 400 Series
1. Fit the piston to the connecting rod with the
wording ‘Camshaft Side’ on the piston to the same
side as the identification marks on the connecting
rod big end and cap.
Figure 2.33.6 Connecting Rod and Cap Identification Marks
2. Place the connecting rod into the piston and
Insert the gudgeon pin and circlips into the
piston. Special care must be taken to ensure the
circlips are correctly and securely located.
3. Fit the piston rings, using a piston ring expander,
taking care to ensure they are fitted in the correct
order.
Figure 2.33.7 Piston Ring and Gap Positions
A - Firing ring; B - Compression ring; C - Oil control ring;
X - Piston ring gap positions
4. Turn the crankshaft journal to TDC.
If necessary, fit new connecting rod big end
bearing shells ensuring they are correctly located
in both the connecting rod and cap.
5. Stagger the piston ring gaps as shown at ‘X’ in
the above illustration.
Each ring gap must be set at 90° to the adjacent
rings and 45° from the gudgeon pin axis.
6. Fit the piston and connecting rod into the cylinder
while compressing the piston rings using a
suitable piston ring compressor.
Ensure the identification marks on the connecting
rod will be facing towards the crankcase door on
final assembly.
7. Push down on the piston crown and turn the
crankshaft anti-clockwise until the big end is
almost at BDC.
8. Ensure the identification marks on the connecting
rod cap and rod are identical and replace the
cap. Fit two new bolts and nuts and torque them
to 35.0Nm (26.0lbf ft).
It is recommended that the bolts are replaced
at every major overhaul. Big end bolts are not
supplied in the overhaul kit.
2.34 Piston oiL jets
CAution
If expansion controlled pistons are being fitted
to replace the early mono-metal type the higher
output oil pump assembly, 750-12020 (fitted as
standard on all engines except turbo), and oil
cooling jets must also be fitted. Oil jet screws
only fitted on engines above 1800rpm.