单项选择题
A.pitting
B.sludge
C.hard varnish
D.all of the above
单项选择题 Surface irregularities, such as erosion and pitting on injection pump plungers, will()
单项选择题 Oil oxidation, as a result of excessively high lube oil temperature, is harmful to a diesel engine because ()
单项选择题 When disassembling or assembling an injection pump plunger and barrel you should ()