18
30/ENGINE
122
202784-10
–
Using a straightedge and the special tool, check the sealing area of the cylinder
head for distortion.
Feeler gauge (59029041100) (
Info
The cylinder size
1
is labeled on the back of the cylinder.
Cylinder/cylinder head - distortion of
sealing area
≤
0.10 mm (
≤
0.0039 in)
» If the measured value does not meet specifications:
–
Change the cylinder.
18.4.8
Cylinder - Nikasil® coating
202785-10
Nikasil
®
is a surface protection layer for a coating procedure developed by Mahle. The
name is derived from the two materials used in this procedure - a layer of nickel into
which is embedded the particularly hard silicone carbide.
The most important advantages of the
Nikasil
®
coating are very good heat conductivity,
resulting in much improved performance, low wear, and a lightweight cylinder.
18.4.9
Checking/measuring the piston
202785-10
–
Check the piston bearing surface for damage.
» If the piston bearing surface is damaged:
–
Replace the piston and, if necessary, the cylinder.
–
Check that the piston rings move easily in the piston ring grooves.
» If the piston ring is stiff:
–
Clean the piston ring groove.
Tip
An old piston ring can be used to clean the piston ring groove.
–
Check the piston rings for damage.
» If the piston ring is damaged:
–
Change the piston ring.
Info
Mount the piston ring with the marking facing upward.
–
Check the piston pins for discoloration or signs of wear.
» If the piston pin shows severe discoloration/signs of wear:
–
Change the piston pin.
–
Place the piston pin in the connecting rod and check the seating for play.
» If the piston pin seating has excessive play:
–
Change the connecting rod and piston pin.
202786-10
–
Measure the piston at the piston skirt, at right angles to the piston pin, at a
distance
A
.
Guideline
Distance
A
50 mm (1.97 in)
Piston - diameter
Size I
66.355… 66.365 mm (2.6124…
2.61279 in)
Size II
66.366… 66.375 mm (2.61283…
2.61318 in)
