Before proceeding to extract the connecting rod and piston assemblies from the engine, it is necessary to remove the cylinder head, oil pan and oil pickup pipe, main bearing cap bridge/oil deflector plate/balancing assembly (depending on the configuration) (see Part SOHC Gasoline Engine Repair Procedures Without Removing Them From The Vehicle, Repair procedures for DOHC gasoline engines without removing them from the vehicle or Procedures for repairing diesel engines without removing them from the vehicle).
1. Using a special countersink, completely remove traces of stepped wear from the top of the cylinders - proceed in accordance with the manufacturer's instructions included with the countersink. The step is formed at the limit of the piston stroke, approximately 6.4 mm below the top edge of the cylinder due to mechanical wear of metal and carbon formation; its presence can be determined by touch with a fingernail. Attempts to remove the connecting rod and piston assemblies without removing the stepped wear are fraught with damage to the pistons.
Removal stepped wear from the top edge of the cylinder using a special countersink
2. Once you have finished preparing the cylinders, turn the engine upside down so that the crankshaft is on top.
3. Before removing the connecting rods from the crankshaft, estimate the amount of axial play of their fit on the corresponding journals of the latter. Insert the blade of the measuring gauge tightly into the gap between the side wall of the lower head of the connecting rod and the crank cheek, completely removing the play of the connecting rod on the journal of the shaft. The total thickness of the selected blades of the gauge will be equal to the value of the axial play of the connecting rod. Compare the result of the measurement with the requirements of the Specifications. If the value of the axial play exceeds the maximum permissible value, this connecting rod is subject to replacement. The axial play of a new connecting rod, or an old one on a new shaft, may be less than the lower permissible limit, in which case the connecting rod can be machined - consult with specialists at the car service. Check all the remaining connecting rods one by one.
Measuring the axial clearance of connecting rod and piston assemblies
4. Make sure that the lower heads of the connecting rods and their caps have identification marks indicating that they belong to your cylinder; if necessary, apply the marks yourself using a small center punch or marker.
Before removing, make sure that the connecting rod caps have identification markings; if necessary, apply them yourself using a marker or a small center punch
5. Turn the crankshaft so that the pistons of the 1st and 4th cylinders are in the BDC positions.
6. In several stages (1/2 turn per approach) loosen the nuts/bolts securing the lower connecting rod cap of the first cylinder so that you can unscrew them manually. Remove the connecting rod cap together with the bearing shell placed in it - try not to drop the latter.
On some engines, the lower connecting rod head section is formed by breaking the blank while preserving the fracture shape by special processing for better joint quality. When removing the caps from connecting rods of this type, exercise extreme caution - do not damage the mating surfaces.
(Original source is on the website opelbook.ru)
7. To protect the shaft journal and cylinder bore, stretch a couple of pieces of suitable sized hose onto the connecting rod lower head mounting studs.
8. Remove the bearing shell from the connecting rod head, then, resting the wooden handle of a hammer on the bearing bed in the lower head, push the connecting rod and piston assembly out of the block through the top of the cylinder. If resistance occurs, immediately stop removing the assembly and make sure that the stepped wear in the upper part of the cylinder has been completely removed.
9. Proceeding in a similar manner, remove the connecting rod and piston assembly of the 4th cylinder from the engine, then turn the engine 180 degrees clockwise and remove the assemblies of the 2nd and 3rd cylinders.
Proceed with extraction only after the connecting rod is positioned strictly parallel to the cylinder axis!
10. To avoid accidental mechanical damage to bearings and loss of components, reinstall the bearing shells and secure the bearing caps to the lower ends of your connecting rods by hand tightening the mounting bolts/nuts.
11. Do not remove the pistons from the connecting rods.
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