In a normally operating diesel engine, the main cause of lubricating oil contamination in the crankcase is a result of the （）.

[单选题]In an operating diesel engine, which of the following conditions is an indication of a leaking air starting valve?A．Noise coming from that air starting valveB．Continuous operation of the starting air compressorC．Zero air pressure in the air starting

[单选题]A diesel engine is operating with excessively high exhaust temperatures at all cylindersTo correct this condition, you should FIRST （）.A . reduce the engine loadB . increase the cooling water flowC . increase the lube oil pressureD . adjust the fuel

[单选题]Operating a diesel engine for prolonged periods, with a closed freshwater cooling system, at temperatures lower than the normal design temperature can cause （）.A . the formation of sulfuric acidB . a decrease in lube oil viscosityC . a decrease in co

[单选题]How should you warm up a diesel engine that has not been run for some time? （）A . Run it at minimum speed for a period of timeB . Run it at half speed for a period of timeC . Bring it to top speed immediatelyD . Inject ether into the air intake

[单选题]The operating diesel generators will have their exhaust temperatures, cooling water and lubricating oil temperatures and pressures （） in much the same way as for the main engine.A . to be keptB . loggedC . changedD . has remained

[单选题]_____ the engines, the diesel engine is ____ used engine on boardA．Between / more commonlyB．Among / the most commonlyC．Between / not more commonlyD．Among / not the most commonly

[单选题]The heart of the diesel engine is the （） where the fuel is burnt and the power developed.A . crankcaseB . cylinderC . scavenge boxD . pisto

[单选题]The diesel engine is a type of （）.A . turbine engineB . gas turbineC . steam engineD . internal combustion engine

[单选题]E．ngine operating conditions may be indicated by the color of the exhaust smoke Black smoke could indicate .A．an insufficient speed droop settingB．an overloaded engineC．clogged drain holes in the oil control ringsD．complete combustion

[单选题]F．or a continuous operation diesel engine, a duplex filter unit would be the best arrangement becauseA．changing filter elements would not interrupt engine operationB．filtering occurs twice in each pass of oil through the systemC．clogging will not occ