Piston/Connecting Rod Assembly — Installation and Clearance Check (Opel Astra F)

Clean the backs of the big-end bearings and the recesses in the connecting rods and big-end caps. If new bearings are being installed, make sure that all grease residue has been washed off with kerosene. Wipe the bearings, caps and connecting rods with a dry, lint-free cloth.

Press the bearing shells into the connecting rod body and cap.

Checking the operating clearance of the big end bearing

Note: When installing the piston/connecting rod assembly, new bearing cap bolts should be installed, but when checking bearing clearance, the old bolts should be used (then thrown out). The operation will require a device for compressing piston rings.

Lubricate piston No.1 and piston rings with engine oil and check the gaps in the ring lock. The lock of the lower steel ring of the oil scraper ring should be shifted by 25-50 mm to the right of the lock of the spacer ring, and the gap of the upper steel ring should be shifted by the same distance to the left. The upper compression ring should be installed with the lock offset by 180° in relation to the lock of the lower compression ring.

Generously lubricate the cylinder bore with clean engine oil.

Install the ring compression device on piston No.1, insert the piston and connecting rod into the cylinder so that the base of the device rests on the block. After turning the crankshaft connecting rod journal to the lowest point, carefully tap the piston into the cylinder using the wooden handle of the hammer and simultaneously direct the connecting rod onto the journal. Note that the arrow (mark) on the piston head should point toward the engine flywheel. The lubrication hole in the connecting rod should be on the side of the engine cooling system pump.









To measure the big-end bearing clearance, follow the instructions in the previous section. If using the Plastigage method, make sure the crankpin and bearings are clean and dry.

Repeat the operations with the remaining piston/connecting rod assemblies.

Final installation of the piston/connecting rod assembly

After checking the clearance, remove all traces of Plastigage from the surface of the bearings and journals.



Generously lubricate the journals and bearings and install the caps. Tighten the new cap bolts in two stages.

After installing each piston/connecting rod assembly, rotate the crankshaft and ensure it rotates freely.

Install the sump deflector (if required), oil supply pipe and sump.

Install the cylinder head.