单项选择题
A.leaking delivery valve
B.excessive bearing end play
C.plugged injector spray hole
D.increased plunger stroke
单项选择题 An efficient seal between the cylinder block and cylinder heads on many diesel engines is obtained with（）
单项选择题 What is the function of the after-cooler installed in the diesel engine air intakes system?（）
单项选择题 Which harmful consequence may be the result of lube oil sludge accumulation? （）