Service procedures - engine Group 21
40
Cylinder liners, measurement
and inspection
This check consists of measuring wear and checking for
cracks.
Clean the cylinder liners thoroughly before measuring them.
Measure wear with a dial indicator.
Measuring is carried out at several positions diametrically,
and also at different heights. To find out the actual amount of
wear, first set the dial indicator with a gauge ring, using the
cylinder liner original bore as a reference measurement.
=0.38 mm (0.0150")
Cylinder liners, honing
For good lubrication and sealing it is important that the liner
walls retain the original honing pattern. See figure. Honing, to
restore the pattern, is therefore to be carried out when:
• the cylinder liner has scratches (ring seizure,
dirt)
• the cylinder liner has bright spots (polishing)
1
Mark the piston and liner before removing to make sure
that the same piston and liner are refitted in the same
place as before
2
Place the cylinder liner in a vise. See figure. Honing of the
cylinder liner when installed in the block is not recommended
due to the risk of oil channels becoming clogged and the diffi-
culties to feed correctly.
3
Remove the carbon edge at the top of the liner. Also clean
under the liner collar and the recess in the block.
4
Use a low speed electric drill with a speed of 200- 400 rpm
and a ”Flex-Hone” tool type GBD. Grade size 80.
Lubricate the cylinder liner with light engine oil before and
during honing. Move the honing tool in and out of the cylinder
liner at 60 strokes/min. (One inward and outward stroke
per second.)
Measure wear using a piston ring (alt.)
Liner wear is easily determined by placing a new piston ring
at the upper turning position and measuring the piston ring
gap. This is then compared with the piston ring gap below
the lower turning point. The wear is determined by dividing
the difference by 3.14.
Example:
Piston ring gap in unworn section: 0.6 mm (0.0236")
Piston ring gap at upper turning point: 1.80 mm (0.0709")
Difference: 1.80 mm–0.60 mm = 1.20 mm (0.0472")
Diameter wear: 1.20 mm
3.14
Wear tolerance:
If the wear is 0.45 - 0.50 mm (0.0177 - 0.0197") the liner
should be replaced. Like pistons, the cylinder liners are clas-
sified which means they must belong to the same class as
the piston. The piston and cylinder liner sets are only availa-
ble from stock as a single, complete unit.
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