单项选择题
Black areas on the sealing surfaces of piston rings indicate（）
A.lube oil pumping
B.rotating rings
C.gas pressure behind the ring
D.passage of hot gases
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相关考题
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单项选择题
When inspecting piston rings through the ports of a two-stroke/cycle diesel engine, black areas on the sealing surfaces are the result of （）
A.insufficient lubrication
B.improper piston cooling
C.blow-by
D.overload operation -
单项选择题
Visual inspection of chrome-plated piston compression rings reveals a black ring face at the position of the cylinder liner portsThis condition indicates a ring which（）
A.has a crown-face
B.exceeds wear limits through normal wear
C.has excessive blow-by
D.is in good condition -
单项选择题
A bright shiny appearance of the sealing surfaces on diesel engine compression rings indicates（）
A.combustion gas blow-by
B.excessive lubrication
C.properly functioning rings
D.insufficient cylinder cooling
