单项选择题
A.excessive lube oil consumption
B.lower than normal lube oil temperature
C.higher than normal exhaust back pressure
D.excessive crankshaft end play
单项选择题 Cold clearances between the skirt of an aluminum piston and the cylinder liner is about （）
单项选择题 Exhaust valve openings in a diesel engine cylinder head are made as large as practical to （）
单项选择题 If the compression rings on a diesel engine piston become stuck in the ring groove, the cause may be due to（）