Lombardini CHD series - Cylinder and Piston Components; Cylinders; Cylinder roughness; Piston

- 36 - Workshop Manual LDW CHD _ cod. 1.5302.345 - 6° ed_rev. 05
)mm(D
10,88÷00,88 001,88
A
10.88÷00.88 769.78÷069.78 050.0÷330.0
4
45
43
42
40 41
46
44
Cylinders
Reset dial gauge with a calibrated ring.
Check diameter size D at 1, 2 and 3; repeat the same operation
at the same places after turning the dial gauge by 90°.
Check for wear in the X area where piston rings are located.
To check clearance with the matching piston measure the
diameter size at Z along the axis which runs at right angles to
the driving shaft.
Class Ø Cylinder
Ø Piston Clearance
Limit value
(mm)
Disassembly / Reassembly
Piston availability
The pistons oversized by 0.5 and 1.0 mm have the uprating reference
onthecrown,g.45-46.
Piston
Remove circlips and piston pin.
Remove piston rings and clean grooves.
Measure diameter Q at the A distance from the bottom of the
skirt (A = 12 mm)
In case of diameter wear exceeding 0.05 mm of the minimum
given value replace piston and rings.
Nota: The oversizes are 0.50 and 1.00 mm. The LDW TURBO
piston differs from that of the NATURALLY ASPIRATED
LDW in its cooling sprayer passage niche and an insert in
theslotoftherstring.
Cylinder roughness
Important
Do not manually hone the cylinder bore surfaces with
emery cloth or other means.
The inclination of the cross-hatched marks left by machining
should range between 115°-140°; they should be uniform and
clearly visible in both directions.
Average roughness should range between 0.5 and 1 mm.
The cylinder surface which comes into contact with the piston
rings should be machine honed with the plateau system.