G424 Service Manual Base Engine Service Procedure164
6En0554
6EN1557
3. Cylinder Boring
(1) Oversize pistons to be used should be determined on
the basis of largest bore cylinder.
(2) Oversize pistons are available in four size 0.50 mm
(0.0197 in.), and 1.00 mm (0.0394 in.). Rebore the
cylinder to a diameter that matches the selected piston
outside diameter that matches the selected piston
outside diameter with the specified clearance. The
reference piston outside diameter measuring point is
shown in the illustration.
(3) Based on the measured piston O.D. calculate the boring
finish dimension.
Boring finish dimension = Piston O.D. + 0.02 to 0.04 mm
(0.0008 to 0.0016 in.) (clearance between piston O.D.
and cylinder ) - 0.02 mm (0.0008 in.) (honing margin)
(4) Bore all cylinders to the calculated boring finish
dimension.
Caution: To prevent distortion that may result from
temperature rise during boring, bore cylinders, working from
No.2 to No.4 to No.1 to No.3.
(5) Hone to the final finish dimension (piston O.D. +
clearance between piston O.D. and cylinder).
(6) Check the clearance between the piston and cylinder.
Standard value:
Clearance between piston and cylinder
0.02 to 0.04 mm (0.0008 to 0.0016 in.)
Installation Service Points
A Crankshaft thrust bearing installation
(1) Install the two thrust bearing in the No.3 bearing bore in
the cylinder block. For easier installation, apply engine
oil to the bearings, this will help fold them in position.
(2) The thrust bearings must be installed with their groove
side toward the crankshaft web.
Thrust
direction
Piston O.D
Groovers
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