4.19. Removal of conrod and piston assemblies

Before starting extraction from the engine of conrod and piston assemblies, it is necessary to remove a head (i) of cylinders, the pallet of a case and the oil pump with a maslozaborny tube.


  1. By means of a special vertical drill completely remove traces of step wear from the top part of cylinders — act according to the instructions of the manufacturer attached to a vertical drill. The step is formed on piston stroke border, approximately in 6.4 mm under the top cut of the cylinder due to mechanical production of metal and a nagaroobrazovaniye, it is possible to determine its existence to the touch by a finger nail. Attempts of extraction of conrod and piston groups without removal of step development are fraught with damage of pistons.
  1. Having finished preparation of cylinders, turn the engine upside down so that the bent shaft appeared from above.
  2. Before removing rods from a bent shaft, estimate the size of their axial side play on necks of the last. Densely enter an edge(s) of the measuring probe into a gap between a sidewall of the lower head of a rod and a cheek of a crank, having completely chosen a rod side play on a shaft neck. Total thickness of the picked-up probe edges will also equal to the size of an axial side play of a rod. Compare result of the taken measurement to requirements of Specifications. If the size of an axial side play exceeds extreme admissible value, this rod is subject to replacement. The axial side play of a new rod, or old on new to a shaft, can appear less than the lower admissible limit, in this case the rod can be pierced — consult with specialists of car service. Serially check all remained rods.
  3. Remove assembly of covers of radical bearings (see Removal of a bent shaft).
  1. Make sure available on the lower heads of rods and their covers of identification tags of belonging to the cylinder — do not mix number of a rod with marking of the size of the conrod bearing (see Check of a condition of components of conrod and piston group). In stages (on 1/2 turns for approach) weaken nuts of fastening of covers of the lower heads of rods so that the possibility of their otvorachivaniye manually appeared. Uncover the first rod together with the bearing insert placed in it — try not to drop the last.

    A — Number is beaten out on a joint of the lower head of a rod with its cover with number of the cylinder — this marking serves for determination of the size of a bearing opening in a head
    B — Marking of accessory of a rod (and covers of its lower head) to a certain cylinder should be put independently by means of a center punch before extraction of assemblies


  1. Take an insert from the lower head of a rod, then, having rested the wooden handle of the hammer against a bearing bed in the lower head, push out conrod and piston assembly at the top of the cylinder at the top of the block. At emergence of resistance immediately stop extraction of assembly and check completeness of removal of step wear in the top part of the cylinder.
  2. In a similar manner take the remained conrod and piston assemblies from the engine.

Installation of the rod which is subject to extraction coaxially to the cylinder is made by the corresponding provorachivaniye of a bent shaft — start extraction only after the rod is located strictly parallel to a cylinder axis!

  1. In order to avoid casual mechanical damage of bearings and loss of components, establish into place inserts and fix covers of bearings on lower heads of the rods, having by hand tightened nuts.