Crankshaft — Checking the condition (BMW 3 Series E46)

Checking axial play

1. To measure axial play, the crankshaft must be in place in the main bearings, but free in the axial direction.

2. Install a dial indicator at the end of the shaft and rest its feeler against the end of the shaft (Fig. 13.2). Move the shaft to one side until it stops and reset the indicator. Now move it to the other side until it stops and read the indicator reading. This is the axial play. Compare the result with the specified play value (see Technical data) and decide whether the thrust bearing needs to be replaced.



3. If you do not have a dial indicator, you can measure the clearance with flat feeler gauges. Move the shaft towards the flywheel and measure the clearance between the crankshaft cheek and the thrust bearing (Fig. 13.3).

Checking the status

4. Wash the crankshaft in kerosene or other suitable solvent. Dry the shaft, preferably with compressed air if possible. Clean the oil holes.

Caution: Wear safety glasses when working with compressed air.

5. Inspect the main and connecting rod journals for excessive wear, scratches, scoring, pitting and cracks.

6. Wear of the lower connecting rod head bearings is indicated by a clearly audible metallic knock when the engine is running (especially when accelerating the engine from low revs), as well as some drop in oil pressure.

7. Wear of the main bearings is accompanied by strong engine vibration and rumble, especially loud when accelerating the engine, as well as a drop in oil pressure.

8. Run your finger along the neck with light pressure - if grooves have developed on the neck. You will easily feel them. In this case, the shaft needs to be turned (if that's still possible) or replace.

9. After turning the journals, check to see if there are any burrs left at the edges of the oil holes. The ends of the holes are usually chamfered, so burrs are unlikely to cause any problems if the turning is done carefully. Burrs can be removed with a scraper or a thin file.

10. Leave the turning of the journals to service station specialists. They will also select new bearings of the repair size.