Checking the clearance between the bearings and the connecting rod journals of the crankshaft (BMW 3 Series E21)

Insert the pistons into the cylinders (without piston rings) with connecting rods in accordance with the cylinder number marks on the piston bottom (the count is carried out from the camshaft drive side). In this case, the arrow on the bottom for orienting the piston in the cylinder must be directed towards the camshaft drive.

Install the connecting rod cap by placing a piece of plastic PG I gauge wire between the unlubricated bearing shell and the connecting rod washer.

Tighten the nuts of the connecting rod cap mounting bolts. Remove the cap and use the scale on the packaging to determine the gap size by flattening the wire.

Remove the pistons with connecting rods through the cylinders.

Insert the piston rings into the cylinders and check the gap in the piston ring lock with a set of feeler gauges. Check the gap between the piston rings and the grooves with a set of feeler gauges, inserting the ring into the corresponding groove, observing their orientation (see picture). If the ring has a TOR (Top) mark, install the ring with the mark facing up (to the piston bottom).



Lubricate the piston grooves and piston rings with engine oil and install the rings on the piston, arranging the ring joints at 180° intervals.



Compress the piston rings with a mandrel and insert the pistons with connecting rods into the cylinders, having previously lubricated their walls with engine oil (point the arrows on the piston bottom towards the camshaft drive).

Lubricate the connecting rod bearing shells and connecting rod journals with engine oil. Install the connecting rod caps onto the crankshaft journals and tighten the connecting rod bolts.

Install the oil pump.

Install the oil pan.

[The website served as the basis for the text: BMWMAN.ru]