Opel Corsa B 1993–2000 Service and Repair Manual: Pistons and connecting rods - removal and refitting

Removal

1. Remove the cylinder head, the sump and the oil pump, as described in earlier Sections.

2. The connecting rod big-end caps and rods may not be marked numerically for location when new and therefore they must be inspected for identification marks before dismantling. If no marks are evident, punch, scribe or file identification marks on the caps and rods starting with No 1 at the timing cover end. Mark them all on the same side to avoid confusion during reassembly. If they have already been marked then this will not, of course, be necessary.

3. Undo and remove the big-end cap retaining bolts and keep them in order for correct refitting.

4. Detach the big-end bearing caps. If stuck, lightly tap them free using a soft-faced mallet.

5. To remove the bearing shells for inspection and/or renewal, press the bearing end opposite the groove in both connecting rod and bearing cap and the shells will slide out.

Again keep the shells in order of removal.

6. The piston rod assemblies are removed through the top of each cylinder bore, being pushed upwards from underneath using a wooden hammer handle which is pushed against the connecting rod. Rotate the crankshaft accordingly to gain suitable access to each rod assembly. Note that, if there is a pronounced wear ridge at the top of the cylinder bore, there is a risk of piston ring damage unless the ridge is first removed using a ridge reaming tool, or scraper.

7. The pistons should not be separated from their connecting rods unless they or the gudgeon pins are to be renewed. The gudgeon pin is a press fit and special tools are required for removing and installation.

This task should therefore be entrusted to your local agent or automotive machine shop.

8. If for any reason the pistons are separated from their rods, mark them numerically on the same side as the rod markings to ensure correct refitting.

Refitting

9. If new pistons or piston rings are being fitted to the old bores, it is essential to roughen the cylinder bore walls slightly with medium grit emery cloth to allow the rings to bed in. Do this with a circular up-and-down action to produce a criss-cross pattern on the cylinder bore walls. Make sure that the bearing journal on the crankshaft is protected with masking tape during this operation.

Thoroughly clean the bores with a paraffin-soaked rag and dry with a lint-free cloth Remove the tape from the crankshaft journals and clean them also.

10. Commence reassembly by lubricating the cylinder bores and crankshaft journals.

11. Space the piston rings around the pistons so that their end gaps are 180º apart. In the case of the oil scraper ring, offset the gaps in the upper and lower rails by 25 to 50 mm to right and left of the end gap of the central section. Offer a piston/connecting rod assembly to its bore, making sure that it is the right way round (see illustration).

Offering the piston to the bore

12. Oil the piston and rings, then fit a piston ring compressor to the piston and tighten it to compress the rings (see illustration).

Piston ring compressor fitted

13. Gently tap the piston through the ring compressor and into its bore using the hammer handle. Guide the connecting rod near to its crankshaft journal and then fit the bearing shell upper half.

14. Ease the connecting rod onto the journal, fit the lower shell to the cap and fit the cap to the rod (see illustration). Refit and tighten the retaining bolts to the specified torque (see illustration).

Fitting a big-end bearing cap

Tightening a big-end bearing cap bolt

15. Repeat the sequence described for the remaining three piston/ connecting rods.

16. Refit the cylinder head, oil pump and sump.

Flywheel - removal and refitting

Removal

1. Remove the clutch assembly and the release bearing.

2. Undo the three bolts and remove the release bearing guide tube.

3. Mark the position of the flywheel in relation to the crankshaft mounting flange or pulley.

4. Wedge a screwdriver between the ring gear teeth and transmission casing and then undo the socket-headed retaining bolts using a multi-tooth key or socket bit (see illustration).

Remove the bolts and withdraw the flywheel.

Flywheel retaining bolts are socket-headed

Refitting

5. Refitting is the reverse sequence to removal. Tighten the flywheel retaining bolts to the specified torque.