22 Questions
What is the primary cause of crankshaft failures?
Incorrect loading or lubrication problems
What can excessive bending loads on a crankshaft cause?
Crankshaft breakage
What is a common cause of bending loads on a crankshaft?
Misalignment of the main bearing bores
What type of load is most likely to cause a break in the connecting rod journal area?
Torsional load
What is a potential consequence of running with excessive clearance in the bearings?
Bending loads on the crankshaft
Why is it important to perform a close inspection after a crankshaft failure?
To determine the cause of the failure
What is the primary cause of the wiping action that wears the surface of the bearing?
Fuel dilution of the engine oil
What is the primary cause of acid formation in the lubricating oil?
Combustion by-products from the fuel
What is the primary effect of fuel dilution on the engine oil?
Reduces the viscosity of the engine oil
What is the primary cause of corrosive damage to the bearings?
Combustion by-products from the fuel
What is the primary cause of metal fatigue in the bearings?
Overloading of the engine
What is the primary effect of coolant contamination on the bearings?
Forms organic acids that attack the bearing material
What is a common cause of crankshaft failure due to machining practices?
Improper grinding of the fillet radius
What is the recommended minimum undersize for crankshaft journals?
0.030" (0.75 mm)
What is a consequence of a lack of lubrication on crankshaft journals?
Metal to metal contact and scoring
What is a common source of contamination in the lubricating oil?
All of the above
What is a characteristic of normal bearing wear?
Exposure of the copper inner layer
What is a consequence of contaminated lubricating oil?
Accelerated wear or damage to crankshaft journals
What is a cause of bearing failure?
Breakdown or loss of the oil film
What is a consequence of a lack of lubrication on bearings?
Rapid destruction of the bearings
What is a source of foreign material in the lubricating oil?
Poor maintenance practices
What is a characteristic of bearing damage due to foreign particle contamination?
Abrasive wear or deep scratches
Learn about common crankshaft failures, their causes, and how to identify them. Understand the role of loading, service procedures, and lubrication in preventing failures. Improve your diagnostic skills and ensure long-term engine reliability.
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