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The function of the piston compression rings used in a diesel engine is to （）
A . seal the space between the piston and liner
B . transmit heat from the piston to the cylinder liner
C . reduce the amount of combustion gas blow-by
D . all of the above
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Excessive piston ring wear in a diesel engine will cause（）
A . high lube oil viscosity
B . increased lube oil consumption
C . low lube oil temperatures
D . high firing pressure
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A diesel engine piston ring face is in direct contact with the （）.
A . top of the ring groove
B . cylinder liner oil film
C . bottom of the ring groove
D . back of the ring groove
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In a four-cycle diesel engine piston blow-by can result in increased（）
A . crankcase pressure
B . compression pressure
C . scavenge pressure
D . exhaust manifold pressure
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In a medium speed diesel engine, a trunk type piston may be cooled by（） Ⅰ.oil circulation though passages in the piston crown Ⅱ.heat transfer through piston rings and liner wall
A . Ⅰ only
B . Ⅱ only
C . either Ⅰ or Ⅱ
D . neither Ⅰ or Ⅱ
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If a diesel engine has been stopped because of piston seizure due to severe overheating, the crankcase（）
A . inspection covers should not be opened until the engine has cooled
B . ventilation system should be continued in operation for one hour for cooling
C . scavenge pump should be immediately secured to prevent loss of lube oil
D . explosion covers should be opened slightly to provide extra ventilatio
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If a four-stroke/cycle diesel engine is started by injecting air into the cylinder, the pistons receiving the charge of starting air must be（）
A . on the power stroke
B . on the exhaust stroke
C . at the end of the power stroke
D . at the start of the intake stroke
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In a diesel engine, when installing new piston rings it is important to check（） Ⅰ.ring gap clearance Ⅱ.side clearance
A . Ⅰ only
B . Ⅱ only
C . both Ⅰ and Ⅱ
D . neither Ⅰnor Ⅱ
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A condition contributing to diesel engine piston rings sticking in the ring grooves, is insufficient ring clearance at the ring（） Ⅰ.gap Ⅱ.side
A . Ⅰonly
B . Ⅱ only
C . both Ⅰ and Ⅱ
D . neither Ⅰ nor Ⅱ
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On a four-stroke diesel engine, when the piston is driven downwards by the expanding gas, it delivers power to the crankshaft through the （）.
A . thrust block
B . sounding rod
C . connecting rod
D . push rod
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（）diesel engines generally have two systems of lubrication:（）a total loss system feeding and a circulating system lubricating the running gear and cooling the pistons.
A . Large crosshead type；crossheads
B . High speed；the cylinders
C . Large crosshead type；the cylinders
D . Four-stroke；pistons and cylinder
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In a trunk type diesel engine piston, the thickness of the head or crown is determined by the（） Ⅰ.statically balanced Ⅱ.heat dissipation requirement
A . Ⅰ only
B . Ⅱ only
C . both Ⅰ and Ⅱ
D . neither Ⅰ nor Ⅱ
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In a diesel engine, excessive cylinder liner wear will cause （） (1) increased blow-by (2) wear between the piston ring and groove
A . (1) only is correct
B . (2) only is correct
C . both (1) and (2) are correct
D . neither (1) or (2) axe correct
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Combustion gases formed in the cylinder of a diesel engine are prevented from blowing past the piston by （）
A . cylinder valves
B . compression rings
C . piston skirts
D . oil ring
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Improperly fitted piston rings in a diesel engine can cause（）
A . excessive lube oil consumption
B . lower than normal lube oil temperature
C . higher than normal exhaust back pressure
D . excessive crankshaft end play
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In diesel engines designed with a crosshead, the motion of the piston rod can be described as （）.
A . reciprocating at the piston pin, rotary at the crank pin
B . reciprocating at the crank pin, rotary at the piston pin
C . straight reciprocation
D . straight rotatio
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Incomplete combustion in a running diesel engine can cause piston rings to become stuck as a result of （）
A . residual carbon deposits
B . lube oil viscosity breakdown
C . uneven heat expansion of the rings
D . uneven heat expansion of the pisto
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In a four-stroke/cycle diesel engine, after the completion of the power stroke, the piston will move（）
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
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When installing rings on a diesel engine piston, you should check the ring（）
A . diametrical tension
B . gap clearance
C . radial thickness
D . face thickne
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During the power stroke of a four-stroke/cycle diesel engine, most of the side thrust of a trunk-type piston is absorbed by the（）
A . piston skirt
B . pinion
C . crosshead
D . compression ring
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Which of the following statements represents the function of the compression rings installed at the top of a diesel Engine piston?（）
A . Control the amount of lube oil burned in the combustion chamber
B . Transmit heat from the piston to the cylinder liner
C . Prevent damage to ring groove inserts by acting as a heat dam
D . Dissipate combustion chamber gas pressure by channeling it through the ring ga
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The pressure in an operating diesel engine cylinder continues to rise for a short period after the piston passes top dead center as a result of the （）
A . expansion of the combustion gases
B . exhaust and intake valves just closing
C . maximum compression is just being attained
D . fuel injection occurring at that point and combustion begi
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If the compression rings on a diesel engine piston become stuck in the ring groove, the cause may be due to（）
A . excessive ring action
B . excessive ring temperature
C . improper ring rotation
D . excessive ring face wear
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When inspecting piston rings through the ports of a two-stroke/cycle diesel engine, black areas on the sealing surfaces are the result of （）
A . insufficient lubrication
B . improper piston cooling
C . blow-by
D . overload operatio
