Piston, Replace
If replacement of the piston or con-rod is necessary on pistons with inserted con-rods, all components of this assembly (piston, piston rings, piston pins and con-rod) must be replaced with new components.
Assemble guide drift from KM-634-6 (1), KM-634-7 (2) and KM-634-5 (3).
Insert new piston in woodruff key groove of KM-634-1 (1). The piston pin bore must be horizontal for this operation.
Fit KM-634-4 (3) to KM-634-1. Tighten fastening bolts to be only handtight.
Tension piston using KM-634-2 (2) securely to prevent it from moving.
Determine press-fit depth of piston pin.
Slide assembly (1) of KM-634-6, KM-634-7 (corresponds in length to the piston pin) and KM-634-5 through piston pin bore and con-rod, until KM-634-7 is seated centrally in the piston. In this position, KM-634-4 (2) must bear against the tip of the assembly (arrows) without any play.
Tighten fastening bolts for KM-634-4.
Withdraw centre section of KM-634-7 from guide drift and replace with new (lubricated) piston pin.
Heat upper con-rod eye of new con-rod with heater plate. Installation temperature: 280 �C up to 320 �C. Place surface of eye flat on heater plate and reduce thermal conduction using fire-resistant brick (Illus. II).
As con-rods have no weight balancing studs, they cannot be reworked.
Installation position: Bead (1) on con-rod is located with arrow opposite base of piston. Arrow on base of piston points towards timing side and bead on con-rod is located on transmission side.
Firmly seated piston pin can not be further pressed. Carry out installation quickly.
Push assembly of KM-634-6, piston pin and KM-634-5 uniformly and without delay through piston pin bore and con-rod until it bears against KM-634-4 free of play (see illus.).
Unbolt KM-634-5 and KM-634-6 (left and right) from piston pins and install piston with con-rod.