Bearings – Section 6.5 Corrosion

Section 6.5
Corrosion

Section 6.5.1
Appearance

The bearing surfaces appear to have holes burned in them by acid. See Figure "Example of Bearing Corrosion" ‪

Figure 1. Example of Bearing Corrosion

Section 6.5.2
Damage

Corrosion is a chemical attack on the bearing layers by the lubricating oil. The appearance can change depending on the alloy of bearing and the type of corrosive agent involved. Lubricating oil has an oxidation inhibitor added, but after extended periods, the additive is depleted.‪

Corrosion can develop during operation when a foreign agent such as fuel, air, coolant, or combustion by-products are introduced to the lubricating oil.‪

Section 6.5.3
Possible Causes

There are several possible causes for the damage:‪

1. Using the wrong type of oil.
2. Not performing the daily maintenance practice on the engine.
3. Overloading of the engine.
4. Failure to change the lubricating oil on recommended schedule.

Section 6.5.4
Recommendation

The recommended maintenance procedures after finding corrosion are:‪

1. Replace bearings.
2. Use recommended oil and additives.
3. Use recommended maintenance practices.
4. Change lubricating oil within the recommended intervals.