In a four-stroke/cycle diesel engine, badly worn intake valve guides can cause excessive（）.

A . crosshead B . crown C . piston rod D . connecting rod

A . fuel injectors B . exhaust valves C . intake valves D . all of the above

A . tension load twice each crankshaft revolution B . compression load during power and compression strokes C . inertia load once every four crankshaft revolutions D . bending loads at bottom and top dead center

A . temperature of the exhaust gases B . energy supplied to the turbocharger C . air pressure to the intake manifold D . purge of exhausted gases from the cylinder

A . before TDC and close after BDC B . after TDC and close after BDC C . before TDC and close before BDC D . after TDC and close before BDC

A . 45 B . 60 C . 90 D . 100

A . supercharging B . scavenging C . turbulence D . swept volume charging

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 pisto

A . has little or no internal friction B . has a lower effective compression ratio C . operates with scavenge air under a positive pressure D . operates without energy absorbing intake and exhaust stroke

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 pisto

A . At zero load the intake manifold pressure is greater than the exhaust manifold pressure B . At full load the intake manifold pressure and exhaust manifold pressure are equal C . At full load the intake manifold pressure is less than the exhaust manifold pressure D . At full load the intake manifold pressure is greater than the exhaust manifold pressure

A . inoperative turbocharger B . inadequate fuel supply C . overload on one cylinder D . unequal load distributio

A . improper venting of the cooling system B . carrying the expansion tank water level too high C . a totally clogged impeller in the cooling water pump D . an incorrectly set cooling system temperature control

A . up and draw in a fresh air charge B . down to burn off fuel C . down to compress the fuel air charge D . up and force out the exhaust gase

A . 525 RPM B . 775 RPM C . 1550 RPM D . 1800 RPM

A . Clogged air intake falters B . Piston blow-by C . A defective after-cooler D . Faulty exhaust valve

A . piston skirt B . pinion C . crosshead D . compression ring

A . twice the crankshaft speed B . half the crankshaft speed C . the same speed as that of the crankshaft D . a speed independent of that of the crankshaft

A . reduce load B . check your exhaust C . adjust cooling water temperature D . increase lube oil flow

A、a circulating system; a total loss system B、a total loss system; a circulating system C、an opened system; a closed system D、a closed system; an opened system

A . The direction of pressure on the journal in four-stroke engine is continuously B . positive feed lubricators are installed on all bearings of four-stroke engine, whereas as a splash feed system is used on tow-stroke engine C . four-stroke engines usually utilize a heavier grade of oil than tow-stroke engines D . Low-stroke engines usually consume less lube oil than four-stroke engine

A . higher working temperature of piston and cylinder B . the use of scavenge ports C . fewer power strokes per revolution of the crankshaft D . part of the fuel is burned as the piston is moving away from top dead center

A . 375 RPM B . 500 RPM C . 750 RPM D . 1500 RPM

A.produce a scavenging effect in the combustion space B.equalize cylinder and exhaust manifold pressures C.alleviate the difference in valve size between the intake and exhaust D.flush out condensate that collects after each compression stroke