The defects found on inspection of the bottom end bearing and pin are; bearing shells may have signs of fretting on the reverse side, there may also be signs of wear or overheating on the shells or signs of pitting on the face or on the back of the shells if they have n't been seating correctly, they should also be checked for signs of pitting or cavitation.
Signs of overheating maybe due to overloading of the engine or lack of oil or from the oil being too hot, cavitation or pitting can be caused by impurities in the oil due to poor filtration, other reasons for poor bearing shell condition are oil dilution from fuel.
The crank pin should be checked for signs of scores which could be from impurities in the hole, the oil hole should be checked to see if it is clear and also the area around the hole should be checked for signs of cracking as this point is a stress raiser.
Other areas to check are the connecting rod bolts, these should be gauged to check for signs of elongation. Also serrations on the mating faces of the bearing cap and connecting rod should be checked for signs of cracks.
Cracks can be located using the dye penetrent method.
Signs of overheating maybe due to overloading of the engine or lack of oil or from the oil being too hot, cavitation or pitting can be caused by impurities in the oil due to poor filtration, other reasons for poor bearing shell condition are oil dilution from fuel.
The crank pin should be checked for signs of scores which could be from impurities in the hole, the oil hole should be checked to see if it is clear and also the area around the hole should be checked for signs of cracking as this point is a stress raiser.
Other areas to check are the connecting rod bolts, these should be gauged to check for signs of elongation. Also serrations on the mating faces of the bearing cap and connecting rod should be checked for signs of cracks.
Cracks can be located using the dye penetrent method.
Comments