
4. Turn round the crankshaft until the piston in ques-
tion is in the lower turning position. Dismantle the
main bearing cap with lower bearing cup.
Fig. 39. Dismantling of piston
5. Place a pair of plastic hoses as protection over the
connecting rod screws. Carefully tap up the con-
necting rod with piston far enough so that the pis-
ton rings are released from the cylinder bore. Lift off
the piston together with the connecting rod.
Note:
Scrape off the soot strip in the top part of the
cylinder bore to simplify dismantling.
6. Dismantle piston ring with a piston ring tongs.
Fig. 40. Dismantling of gudgeon pin
7. Remove the
for the gudgeon pin and dis-
mantle the gudgeon pin carefully with a suitable
mandrel.
I nspection and matching of piston rings
Check the wear surfaces and sides. Black patches on
the surfaces imply poor contact and indicate that it is
time to change the piston rings. The oil consumption is
also a critical factor as to when a piston ring should be
replaced.
Check the piston ring gap (Fig. 41). Push down the ring
below the lower turning position
by means of a pis-
ton. Replace the piston ring if the gap exceeds 1.0 mm
(.039 in).
Fig. 41. Checking of piston ring gap
Piston rings should also be replaced if there is noticea-
ble wear or out-of-roundness in the cylinders since the
rings seldom have the same position as they had before
dismantling.
Check the piston ring gap also on new rings.
See "Technical data" for size info.
Check the clearance in the piston ring groove. Roll the
ring in its groove in the piston and measure the clear-
ance at a number of points with a feeler gauge.
Engine body
35
Содержание MD2010
Страница 1: ...Workshop Manual Engine MD2010 MD2020 MD2030 MD2040 A 2 0 ...
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Страница 80: ...Notes ...