Engine Diagnosis Quiz 2/12

Is gas at the spark plug?

• Flooded

• Dry

Answer explanation

If gas is at the spark plug, it indicates that the engine is flooded. A flooded engine occurs when too much fuel enters the combustion chamber, preventing proper ignition. Therefore, the correct answer is 'Flooded'.

Is there spark? Is the gap correct? 0.25-0.030?

• The question has a diagram associated with it. The diagram has been stored separately.

• No, the gap is incorrect.

• Yes, the gap is correct.

• There is no spark.

Answer explanation

The question references a diagram that is crucial for determining the correctness of the gap. Without the diagram, we cannot definitively assess the gap or the presence of a spark.

Compression is ... ? On compression stroke (4 or 2 Stroke, Diesel) Piston travels up Valves closed/sealed Piston/rings/cylinder/gasket are sealed Need to be timed properly

• Piston travels down

• Valves open

• Piston travels up

• Piston/rings/cylinder/gasket are not sealed

Answer explanation

During the compression stroke, the piston travels up while the valves remain closed. This ensures that the piston, rings, cylinder, and gasket are sealed, allowing for effective compression in the engine.

What is one possible cause of compression loss due to worn or damaged valves?

• Loose head bolts

• Push rod/tappet

• Blown head gasket

• Timing off

Answer explanation

Worn or damaged valves can lead to compression loss, and issues with the push rod or tappet can affect valve operation, causing improper sealing. This makes 'Push rod/tappet' a valid cause of compression loss.

Which of the following can lead to compression loss due to loose components?

• Loose head bolts/spark plug

• Damaged piston/rings/cylinder

• Blown head gasket

• Timing off

Answer explanation

Loose head bolts or spark plugs can cause a loss of compression as they may not maintain proper sealing, leading to leaks. This directly affects engine performance, making this the correct choice.

A 'Worn valve' has what impact on compression loss in the valve train?

• No impact

• Increases compression loss

• Decreases compression loss

• Improves valve efficiency

Answer explanation

A worn valve can lead to improper sealing, allowing air to escape during the compression stroke. This results in increased compression loss, making 'Increases compression loss' the correct choice.

How can 'bent, broken' components affect compression loss in the valve train?

• They can cause increased compression loss.

• They have no effect on compression loss.

• They improve compression efficiency.

• They only affect the exhaust system.

Answer explanation

Bent or broken components in the valve train can disrupt the sealing surfaces, leading to increased gaps. This results in a loss of compression, making the correct choice 'They can cause increased compression loss.'

What are some simple repairs for valve train issues related to compression loss?

• Valve adjustment

• Replace head or block

• Replace valve seat

• Replace valve

Answer explanation

Valve adjustment is a simple repair that can help restore proper clearance and function in the valve train, addressing compression loss. Other options like replacing the head or valve are more complex and costly.

Fill in the blank: To address compression loss, one might need to lap _______.

• valves.

• pistons.

• cylinders.

• gaskets.

Answer explanation

To address compression loss, lapping valves is necessary as it ensures a proper seal between the valve and the seat, preventing leaks. This is crucial for maintaining engine performance and efficiency.

What is a potential cause of compression loss involving the piston?

• Blown head gasket

• Timing off

• Damaged piston/rings/cylinder

• Loose head bolts/spark plug

Answer explanation

A damaged piston, rings, or cylinder can lead to compression loss as they are critical for maintaining the seal necessary for proper compression. This makes 'Damaged piston/rings/cylinder' the correct choice.