Trunk engine piston seizure:
Causes:
1. Blocked coolant supply to piston.
2. Overheating of the unit.
3. Exhaust valve damaged.
4. Rings damaged.
Causes:
1. Blocked coolant supply to piston.
2. Overheating of the unit.
3. Exhaust valve damaged.
4. Rings damaged.
Burning away of piston crown:
Causes:
1. Piston’s inside cooling gallery, fouled with deposits.
2. Incorrect spray angle of fuel valve.
3. Injection viscosity too high.
4. Fuel containing excess amount of water. [Maintain separation temperature 98°C and minimum throughput.]
Causes:
1. Piston’s inside cooling gallery, fouled with deposits.
2. Incorrect spray angle of fuel valve.
3. Injection viscosity too high.
4. Fuel containing excess amount of water. [Maintain separation temperature 98°C and minimum throughput.]
Corrosion of crank pin:
Causes:
1. L.O. contaminated with SW or FW, due to leakage. [ When combustion products, SO₂, enter crankcase, through blow pass ( trunk type) or defective diaphragm (crosshead type), they react with water and form H₂SO₄ and attack crankshaft.]
2. By galvanic action, when crankcase LO is contaminated with SW.
3. Faulty purification system cause LO contaminated with FW.
4. Piston cooling system, leaking into crankcase.
Causes:
1. L.O. contaminated with SW or FW, due to leakage. [ When combustion products, SO₂, enter crankcase, through blow pass ( trunk type) or defective diaphragm (crosshead type), they react with water and form H₂SO₄ and attack crankshaft.]
2. By galvanic action, when crankcase LO is contaminated with SW.
3. Faulty purification system cause LO contaminated with FW.
4. Piston cooling system, leaking into crankcase.
White metal bearing failure:
Causes:
1. Edge carrying wear [Due to out of true of bearing bore, or deviation from journal geometry]
2. Striations wear [Striation and embedding of foreign particles on running surfaces.]
3. Overheating of layer [Due to lack of lubrication and contamination of LO.]
4. Erosion wears [Some abrasive particles carried along with LO.]
5. Electro erosion [If crankshaft is inadequately grounded.]
6. Corrosion [Contamination of LO with SW.]
Causes:
1. Edge carrying wear [Due to out of true of bearing bore, or deviation from journal geometry]
2. Striations wear [Striation and embedding of foreign particles on running surfaces.]
3. Overheating of layer [Due to lack of lubrication and contamination of LO.]
4. Erosion wears [Some abrasive particles carried along with LO.]
5. Electro erosion [If crankshaft is inadequately grounded.]
6. Corrosion [Contamination of LO with SW.]
Broken piston ring:
Causes:
1. Insufficient ring and groove clearance [Vertical clearance: 0.4 mm for top ring: 0.2 mm for lower rings.]
2. Insufficient ring gap. [Butt clearance: 0.5% of cylinder bore, for moderate rating and 1.0% for higher rating. Over 500 mm bore.]
3. Excessive liner wears.
4. Excessive relieving at ring edge. [Oil wedge action cannot be attained.]
5. Insufficient lubrication.
6. Excessive lubrication. [Excessive ring zone deposits and fouling of grooves and micro-seizure may occur.]
7. Improper ring material.
8. Misalignment of piston.
9. Improper fitting.
10. After burning.
Causes:
1. Insufficient ring and groove clearance [Vertical clearance: 0.4 mm for top ring: 0.2 mm for lower rings.]
2. Insufficient ring gap. [Butt clearance: 0.5% of cylinder bore, for moderate rating and 1.0% for higher rating. Over 500 mm bore.]
3. Excessive liner wears.
4. Excessive relieving at ring edge. [Oil wedge action cannot be attained.]
5. Insufficient lubrication.
6. Excessive lubrication. [Excessive ring zone deposits and fouling of grooves and micro-seizure may occur.]
7. Improper ring material.
8. Misalignment of piston.
9. Improper fitting.
10. After burning.
No comments:
Post a Comment