Checking the clearance between the bearing shells and the main journals of the crankshaft (BMW 3 Series E21)

Install the ungreased lower main bearing shells into the cylinder block seats (axial fixation of the crankshaft is provided by liners with cheeks of the middle main bearing).

Place a clean and dry crankshaft into the main bearings.

Install the main bearing cap with the liner in accordance with the installation marks, having first placed a piece of calibrated plastic wire type PG 1 on the surface of the journal.

Tighten the main bearing cap bolt to the specified torque.

Remove the cover and, using the scale on the packaging and by flattening the wire, determine the gap between the bearing shell and the main journal, which should be within 0.030-0.068 mm for a crankshaft with a blue index and 0.030-0.070 mm for a crankshaft with a red index.

Remove the wire, wipe the main journals with a dry cloth, lubricate the main bearings with engine oil, install the covers and tighten the bolts that secure them.

This article is based on data from the website: BMWMan