Dimensional Check And Overhaul Of Cylinders; Dimensional Check And Overhaul Of Pistons - Kohler Lombardini LDW FOCS 502 Euro 2 Service Manual

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6.2.2 Dimensional check and overhaul of cylinders

1. Place the engine block on the workbench.
2. Using a micrometer, measure the diameter at points
1-2-3 (see diagram).
3. Rotate the micrometer 90° and remeasure. If ovalization
or wear is greater than 0.05mm, the cylinder must
be ground .
Important
• The increases recommended by the manufacturer for
the cylinder head 0.5 and 1 mm.
• When grinding make sure that the working angle is
45-55° and that the average roughness is Ra=0.5-1.
• Do not sand the internal surfaces of the cylinders
using emery cloth.
• Protect the contact surfaces with lubricant oil, to
prevent them from rusting
The table shows the reference values and their class
(only applies to new engines).
Important
• Pistons with nominal diameter are supplied only in
class (A) spares. Those uprated by 0.5 and 1 mm
have the uprating referance (ø72.5 e ø73) engraved
on the upper part of the piston (see "Table of cylinder
- piston classes and dimensions").

6.2.3 Dimensional check and overhaul of pistons

1. Clean the piston thoroughly (D).
2. Using a micrometer, measure the piston 9mm from the
base of the skirt.
3. Check the table to identify the class from the values
detected.The class letter is engraved on the piston,
If clearance between cylinder and piston is greater
than 0.05mm, the piston and sealing rings must
be replaced, and rematched according to the
diameter of the ground cylinders "see Table of
cylinder-piston classes and dimensions").
Important
• Before replacing the pistons, check that the weight
difference does not exceed 4g to prevent weight
imbalances.
• Protect the contact surfaces with lubricant oil, to
prevent them from rusting.
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OVERHAULS AND TUNING
Service Manual LDW FOCS 502 automotive _ cod. ED0053027270 - 3° ed_rev. 02
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Tabela classes e dimensões dos cilindros – pistões Table of cylinder - piston classes and dimensions - ( Euro 2 )
Dimension Classe Ø Cylinders Ø cilindros
(mm)
dimensional class (mm)
A 71.990÷72,000
B
72,000÷72,010
C 72,010÷72,020
Table of cylinder - piston classes and dimensions - ( Euro 4 ) Tabela classes e dimensões dos cilindros – pistões Tabela classes e dimensões dos cilindros – pistões
Classe Classe Ø cilindros Ø cilindros
Dimension Ø Cylinders
(mm) (mm)
dimensional dimensional class (mm)
A 71.490÷71,500
B 71,500÷71,510
C 71,510÷71,520
D
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- ( Euro 2 )
Ø pistons Ø pistões clearance folga
(mm) (mm)
(mm) (mm)
71,930÷71,940
71,940÷71,950 0,05÷0,07
71,950÷71,960
Ø pistões Ø pistões folga folga
Ø pistons clearance
(mm) (mm) (mm) (mm)
(mm) (mm)
71,450÷71,440
71,450÷71,460 0,04÷0,06
71,460÷71,470