Bearings – Section 6.1 Oil Contamination

Section 6.1
Oil Contamination

Section 6.1.1
Appearance

The bearing appears to have lines of light scratches or deep grooves. Speckles from embedded particles my be present. Spots of exposed copper layer would show in the lining. See Figure "Example of Oil Contamination" .‪

Figure 1. Example of Oil Contamination

Section 6.1.2
Damage

Oil contamination occurs when foreign particles enter the oil. Normally the oil filter will filter out a great majority of the particles. When there are excessive particles, they can do damage to the bearings. See Figure "Elements of Bearing Damage from Oil Contamination" .‪

1. Journal‪	4. Oil Clearance‪
2. Bearing Lining‪	5. Dirt Particle‪
3. Bearing Backing‪	6. Displaced Bearing Material‪

Figure 2. Elements of Bearing Damage from Oil Contamination

Smaller particles can become embedded in the soft bearing lining, causing the adjacent material to surround the material forming a halo. The larger particles circulate through the clearance between the bearing and the journal, grooving the surface of the bearing in a circumferential manner. The grooves can range from light scratches to deep gouges.‪

Section 6.1.3
Possible Causes

There are several possible causes for this damage: ‪

1. Failure to follow the correct cleaning procedure after rebuild.
2. Not performing the daily maintenance practice on the engine.
3. Wear of the engine parts.
4. Failure to change the lubricating oil within the recommended schedule.

Section 6.1.4
Recommendation

The recommended maintenance procedures after oil contamination are:‪

1. Replace bearings.
2. Check all other engine bearings for similar wear.
3. Use recommended maintenance practices.