Vaz 21213, Руководство по ремонту, Страница: 21 / 222

There is practically no wear in the land 1 area of the cylin-
ders. Compare the values measured on the first and other cylin-
der lands to see the amount of the cylinder wear.
When the maximum wear is over 0.15 mm, rebore the cylin-
ders to the nearest oversize; provide 0.03 mm honing allowance
on the diameter. Hone the cylinder walls so that the difference
between the oversize piston diameter and cylinder bore is 0.025
- 0.045 mm.
Pistons and connecting rods
General Description
The basic sizes of the pistons and connecting rods are
shown in Fig.2-29.
Piston
is an aluminium casting. The piston weight is
precisely maintained during the manufacturing process.
Consequently, there is no need to select the matching piston of
the same weight class during the engine assembly.
There are five classes (Ä, Ç, ë, D, Ö) of the piston according
to their major diameter, in steps of 0.01 mm. The piston has a
complex outside shape: tapered in height and oval in the cross-
section area. Therefore, the piston diameter must be measured
in the plane normal to the gudgeon pin at 55 mm from the piston
crown.
There are three classes (1, 2, 3) of pistons, as to the hole for
the gudgeon pin, in step of 0.004 mm. The classes of piston
diameters and holes for the gudgeon pin are stamped on the pis-
ton crown (Fig.2-30).
The oversize piston major diameter is 0.4 or 0.8 mm bigger.
The 0.4 step is marked in the form of a triangle, while the 0.8 mm
step is marked as a square.
Use the arrow on the piston crown for correct piston orienta-
tion and fitting within the cylinder. The arrow of the piston must
face the timing belt end of the engine.
Gudgeon pin
is of steel, hollow, floating-type, i.e. freely
operates in the piston bosses and connecting rod bush. The gud-
geon pin is secured in the hole with two circlips.
As to the outside diameter the gudgeon pin are of three
classes in step of 0.004 mm. The class is paint marked on the
gudgeon pin face: 1st class - blue paint, 2nd class - green paint,
3rd class - red paint.
Piston rings
are of cast iron. The top compression ring has
a chromed barrel face. The bottom compression ring is of the
scraper type. The oil control piston ring features chromed work-
ing edges and has a coil expander (spreader ring).
The oversize rings are marked as 40 or 80, which corre-
sponds respectively to 0.4 or 0.8 mm step in the major diameter.
Connecting rod
is of forged steel.The connecting rod is
machined together with the big end cap, therefore they are inter-
related. The cylinder number (6 in Fig.2-30) is stamped on the
caps and connecting rods to prevent confusion when refitting into
the cylinders. During reassembly the figures on the connecting
rod and cap should face the same side.
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Fig.2-28. Measuring the cylinder bore:
A and B - direction of measurement; 1, 2, 3 and 4 - No of lands
Fig.2-29. Basic dimensions of pistons and connecting rods