Inspection
1. Check the mating surfaces of the connecting rod caps for any attempts to assemble them with the wrong orientation. This is unlikely, but if this damage is found, the connecting rods and caps must be replaced.
2. Check visually that the connecting rods are not bent, if necessary, for a more detailed check, contact your Opel dealer.
3. Piston pins are used to secure the piston to the connecting rod. Separating the pistons and connecting rods requires special tools, so we advise you to contact your dealer when performing this work.
4. Inspect the pistons for ovality and scratches.
5. If new rings will be installed on the old pistons, remove the old ones through the top of the pistons. Use three old probes for this. Please note that the oil scraper ring consists of three parts. Also, note the orientation of each ring (see illustrations).
Recovery
6. Before installing new rings on the pistons, insert them into the corresponding channels of the cylinders and check with feelers that the clearances of the ring cuts are within the limits specified in Specifications (see illustration). Check the gaps of the ring cuts at the top and bottom of the piston stroke in the cylinder bore.
7. If the gap clearance of any ring exceeds that specified in Specifications tolerance, these rings must be replaced, and if the ring grooves in the pistons are worn out, new pistons will be required.
8. Clean the piston ring grooves with a piece of the old piston ring. Be careful not to scratch the surface of the pistons. Also check the oil return holes in the grooves to make sure they are not clogged.
9. Check up, that in tops of channels of cylinders there were no wear crests.
If there is a wear step when installing new piston rings, the top edge of the upper ring must be ground off so that it does not hit the wear ledge, or the ledge must be ground off.
10 Install the parts of the oil scraper ring so that the lower part is offset 25-50 mm to the right of the center part cut gap, and the upper part is shifted the same distance to the left of the center part cut gap.
11. When installing the lower compression ring, remember that the ring has a conical shape in cross section. It must be set by the word "TOR" up.
12. Install the upper compression ring by shifting the gap of the ring cut by 180°relative to the gap of the bottom compression ring cut. If a stepped ring is being installed, install it with the smaller diameter facing up.
13. If new pistons need to be installed, they must be selected from the available repair sizes, having previously measured the diameter of the cylinder bores, as described in Chapter 36.
14. Usually the required oversize pistons are provided by the dealer after the cylinder block has been bored out.
15. Whenever new piston rings are installed, the cylinder bores must be honed (those. remove gloss from them), for this you can use a skin or a special tool. If skin is used, move at an angle of 60°to the center line of the canal to form criss-cross strokes.
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