With reference to engine system oil-
a) Discuss four contaminants commonly found in engine system oil and their adverse effect of function of oil.
   b) Source of these contaminants and how they detected.
   c) Corrective measures to be taken in case of contamination with contaminants identified in (a)

a. Contaminants commonly found in engine system oil:

I) water contamination:

Effect:

1. Emulsification of oil.
2. Bacterial degradation.
3. Increase the viscosity & density of oil.
4. Reduction in load carrying capacity.
5. Damage to ceramic coatings.
6. Pitting due to stray electric current.

II. Fuel Oil Contamination:

Effect:

• Drop in flash point and affect film formation.
• Increase in density and viscosity resulting in reduced oil flow and increased wear
• Increase ash content
• Increase in abrasive wear.
• Reduce TBN
• Can cause acidic corrosion.

III. Products of combustion:

Effect:

• Increase in density and viscosity resulting in reduced oil flow and increased wear
• Increase the ash content in the fuel
• Increase abrasive wear
• Scuffing or micro-seizure on 4 stroke engines.

IV. Wear Particles:

Effect:

• Increase abrasive wear
• Scoring of JOURNAL & bearing surfaces
• Frequent clogging of filters

b. Sources of these contamination and detection:

I. Water Contamination:

Sources:

• Leakage in exhaust valve, liner O-rings, lub oil cooler.
• Maintaining L.O purifier oil-water interface too close to clean oil outlet.
• Condensation due to high humidity.
• Bilge leakages likely through sump level indicator/damage diaphragm between sump and engine
• Purifier heater steam leakage

Detection:

• Sump level will increase.
• Colour will change due to emulsification.
• Board Water test.
• Laboratory test.

II. Fuel Contamination:

Sources:

• leaky fuel injectors.
• Excessively worn fuel pump plunger & barrel.

Detection:

• Sump level will increase.
• Colour change.
• System LO pressure will be low indicating gas oil contamination.
• Drop in flash point.
• Increase in viscosity and density

III. Products of ontamination:

Sources:

• Excessive blow past.
• If poor sealing between piston rings and liner, this combustion products will enter the system oil directly in trunk type engine.
• If faulty piston gland, this combustion products will enter the system oil in cross head type engine.

Detection:

• Color will change.
• Spot test.
• Frequent clogging of filters.

IV. Wear Particles:

Sources:

• Worn particles from piston ring and liner
• Worn particles from bearing, journal, and crankpin.

Detection

• Colour change
• Spot test
• Frequent Filter clog

IV. Corrective Action:

i. Water Contamination:

• Batch purification at first opportunity.
• Identify and rectify leakages.
• Centrifuge at optimal throughput and maintain temperature at about 80°C-90°C.
• Shipboard and lab analysis should be carried out regularly.

ii. Fuel Contamination:

• Stop source of fuel contamination.
• Overhaul fuel pumps, injectors regularly ENSURE NO LEAKAGE

III. Products of Contamination:

• Ensure no blow past.
• Overhaul fuel pumps, injectors regularly ENSURE NO LEAKAGE
• Shipboard and lab analysis should be carried out regularly.

IV. Wear Particles:

• Carry out batch purification at first opportunity.
• Ensure good purification with optimal throughput.
• Frequent cleaning of filters.
• Clean crankcase after every unit overhaul.
• Frequent spot test/ blot test/ drop test.