单项选择题
A.cause blow-by
B.chemically attack the piston skirt
C.form an emulsion of lube oil and water
D.raise the piston temperature
单项选择题 Which condition indicates the air side fouling of an after-cooler on a turbocharged diesel engine?（）
单项选择题 Black areas on the sealing surfaces of piston rings indicate（）
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 （）