Piston
Maintenance / Disassembly
A5.05. 02.06.01.01
M20
en / 31.05.2010 IB004750 2/3
02
6. Fill the ring gap between piston (3)and cylinder liner (4) with grease.
7. Carefully scrape off and completely remove carbon deposits in the liner (4) ) between TDC of the
first piston ring and the lower edge of the calibrating ring (5).
8. Clean the groove in the calibrating ring (5).
9. Spray a thin film of rust removal spray „Caramba“ in the ring gap between calibrating ring (5) and
liner (4).
10. Allow the rust removal spray to react.
11. To loosen the calibrating ring (5) slightly beat it with a copper hammer until you can turn the guide
of the calibrating ring by hand.
12. Turn piston (3) with turning rod (W3) approx. 50° to TDC.
13. Insert thrust ring (W1.2) and compressed snap ring (6) until the lower edge rests on the piston.
14. Carefully turn piston (3) and thrust ring (W1.2) upwards until the snap ring (6) is engaged in the
groove of the calibrating ring (5).
15. Turn piston (3) further upwards and press out the calibrating ring (5. ). Watch the position of the
calibrating ring.
16. Remove calibrating ring (5) and thrust ring (W1.2).
17. Dismount big-end bearing cover (02.04.01.nn).
18. Turn piston (3) in TDC position, re-tap threaded hole (M12, 11 mm deep) in piston head.
CAUTION
The sealing surfaces of the cylinder liner have to be protected against damage!
NOTE
Do not damage the surface of the liner !
CAUTION
In case the calibrating ring is tilted, you have to lower the piston and align the calibra-
ting ring.
The connecting-rod must not strike on the crank pin. Turn crank pin aside, if neces-
sary.
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