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單項(xiàng)選擇題

If the firing pressures in a diesel engine are high, although the exhaust temperatures are normal, the cause may be（）

A.early injection timing
B.worn orifices in the injection nozzles
C.worn or scored cylinder liners
D.using a fuel with too low of a cetane number

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單項(xiàng)選擇題

Scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished（）

A.during the valve overlap period
B.with only the exhaust valve open
C.at a pressure below atmospheric
D.without cooling the cylinders or pistons

單項(xiàng)選擇題

A diesel engine piston crown can crack from （）

A.excessive piston to liner clearance
B.excessive dirt beneath the piston crown that reduces heat transfer
C.faulty nozzle spray
D.all of the above