MAK M20, Operating Instructions Manual

Page: 285 / 456

Piston Rings and Grooves
Inspection / Checking
A5.05. 02.07.01.01
7500, 30000
M20
en / 16.07.2001 IB021477 2/3
02
Ĺ
1.4 Remove the piston rings only with the
correct tool (
Fig. 1
/W1). Maintain
previous position of the rings referring
to the mounting position of the piston
given in the measuring sheet.
1.5 Clean piston rings.
1.6 Check the the chrome layer for wear,
especially at the cut and at the opposite
side. Renew all rings of this piston even
if only parts of the chrome layer is no
longer visible.
If the chrome layer of one piston ring
has been worn, check the rings of all
pistons.
1.7 Clean the piston, ring grooves and oil return holes for the scraper scraper ring.
1.8 Smooth slight friction and seizing marks with an oily fine emery cloth or fine carborundum
stone. Renew the piston in case of heavy damage or deep scores.
1.9 Measure the groove width
h
N
(
Fig. 2
) in the front area of the groove in longitudinal and
transverse directions of the engine. When exceeding the limits, have the ring grooves
reconditioned by MaK.
1.10 Measure the ring thickness
h
R
(
Fig. 2
) at 4 different points.
h
N1
= new
h
N2
= worn
W1
Fig. 1
h N
h R h N
Fig. 2
1
2