30/ENGINE - WORK ON INDIVIDUAL PARTS 103
400376-10
– Check the sealing area of the cylinder head for distortion using a straight edge and
the special tool.
Feeler gauge (59029041100) ( p. 196)
Cylinder/cylinder head - sealing area
distortion
≤ 0.05 mm (≤ 0.002 in)
» If the measured value does not equal the specified value:
– Change the cylinder.
20.13Checking/measuring the piston
200160-10
– Check the piston bearing surface for damage.
» If the piston bearing surface is damaged:
– Change the piston and, if necessary, the cylinder.
– Check that the piston rings can move easily in the piston ring grooves.
» If the piston ring is stiff:
– Clean the piston ring groove.
Tip
Use an old piston ring 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.
400484-10
– Use the special tool to measure clearance of the piston rings in the piston ring
groove.
Guideline
Piston ring - groove clearance
First ring (L-ring) ≤ 0.105 mm (≤ 0.00413 in)
Second ring (tapered compression
piston ring)
≤ 0.210 mm (≤ 0.00827 in)
Oil scraper ring ≤ 0.180 mm (≤ 0.00709 in)
Feeler gauge (59029041100) ( p. 196)
» If clearance is larger than the specified value:
– Change the piston and piston rings.
– Check/measure the cylinder. ( p. 102)
– Check the piston pin for discoloration or signs of wear.
» If the piston pin has strong discoloration/signs of wear:
– Change the piston pin.
– Insert the piston pin into the connecting rod and check the bearing for play.
» If the piston pin bearing has too much play:
– Change the connecting rod and the piston pin.
200475-10
– Measure the piston on the piston skirt.
Guideline
Piston - diameter
Size I 102.955… 102.985 mm (4.05334…
4.05452 in)
Size II 102.965… 102.995 mm (4.05373…
4.05491 in)
Under the edge at right angles to the
piston pin
6 mm (0.24 in)
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