Test 1

Question 1

What is one of the main functions of a piston?

Answer 1

Transmit force to the crankshaft through the connecting rod

Question 2

Why is the shape of the piston dome important?

Answer 2

To help create turbulence ensuring full combustion

Question 3

How does a ‘Cam Ground’ piston work?

Answer 3

It becomes oval as the engine warms up

Question 4

Why would the top ring groove in an aluminum piston have a steel or nickel-chrome alloy insert installed?

Answer 4

It reinforces and reduces wear in the groove

Question 5

What is a full floating piston pin?

Answer 5

A pin that can rotate freely in the piston and the connecting rod

Question 6

What is the advantage of a two-piece piston?

Answer 6

Both the skirt does not absorb the force of combustion and bending stress on the piston pin is reduced

Question 7

What is the procedure for installing a full floating piston pin that is tight in the piston pin bore?

Answer 7

Use a press to push the piston onto the pin

Question 8

What are the common types of oil cooling for pistons?

Answer 8

Splash, shaker, swirl, circulation

Question 9

What are the functions of a piston ring?

Answer 9

Seal, cool, center

Question 10

What three factors combine to produce an effective seal between the ring and the cylinder wall?

Answer 10

Ring tension, oil film, cylinder pressure

Question 11

What is the main purpose of ring end gap?

Answer 11

Allows a metered amount of blow by into the crankcase

The ring end gap is crucial for controlling the pressure within the combustion chamber and preventing excessive pressure build-up.

Question 12

Most diesel engines today use what type of oil control ring?

Answer 12

Two Piece

Two-piece oil control rings are common due to their efficiency in managing oil consumption.

Question 13

What does a coil or wave expander do for the oil control ring?

Answer 13

Ensures the oil ring has enough tension on the cylinder wall

This helps maintain effective oil control and reduces oil consumption.

Question 14

What is the ‘General Rule’ when installing piston rings?

Answer 14

Install them so at the end gaps are lined up

Proper alignment of ring gaps is critical to prevent excessive blow-by and maintain compression.

Question 15

How is oil controlled in a two-stroke engine?

Answer 15

2 stroke engines have inlet ports on the cylinder wall

This design allows for a different oil management strategy compared to four-stroke engines.

Question 16

What are common types of ring joints?

Answer 16

• Butt
• Angle
• Step

The choice of ring joint affects the sealing and performance of the piston rings.

Question 17

What is used to remove the wear ridge on a cylinder liner?

Answer 17

Ridge reamer

Removing the wear ridge is essential for proper piston and ring installation.

Question 18

What important step should be followed when performing an ‘in Frame’ overhaul?

Answer 18

Cover oil holes and coolant passages to prevent contamination

Preventing contamination is vital for the longevity and performance of the engine after an overhaul.

Question 19

What is the best way to remove a compression ring off of a piston?

Answer 19

Use a universal or fixed expander and slide the ring off the bottom of the piston

This method minimizes the risk of damaging the ring or piston.

Question 20

When should a two-piece piston be disassembled?

Answer 20

Before cleaning and inspection

Disassembling before cleaning ensures thorough inspection and maintenance.

Question 21

What should be done before removing a piston?

Answer 21

Measure the clearance between the piston and liner

This measurement is crucial for ensuring proper fit and function after reassembly.

Question 22

What type of damage would be seen on the piston skirt?

Answer 22

• Erosion
• Scuffing
• Scoring

Damage to the piston skirt can affect engine performance and longevity.

Question 23

What could cause a piston to become overheated?

Answer 23

Insufficient lubrication or excessive load

Overheating can lead to serious engine damage and failure.

Question 24

Why is the piping diameter measurement taken 90 degrees?

Answer 24

The measurement provides a true indication of diameter

Measuring at 90 degrees ensures accuracy in assessing wear and fit.

Question 25

How is the keystone ring groove measured for wear?

Answer 25

Using a micrometer to assess groove depth and width

Accurate measurement of wear is essential for determining if replacement is necessary.

Question 26

What is the method used to measure the keystone ring groove for wear?

Answer 26

With a ring groove wear gauge

Other tools such as feeler gauges, depth micrometers, and dial gauges could also be used in different contexts.

Question 27

What precautions should be taken when bead blasting a piston pin?

Answer 27

Tape off bearing surfaces

Other considerations include turning down the pressure and avoiding aiming the stream at one spot.

Question 28

What does ridging refer to in relation to a piston pin?

Answer 28

Uneven, extreme wear on the piston pin

It can also relate to damage on the connecting rod bores.

Question 29

What is a sign of excessive piston pin clearance in an engine?

Answer 29

A ‘double knock’ from an engine

This symptom indicates potential issues with engine performance.

Question 30

In what orientation should a piston pin snap ring be installed?

Answer 30

Gap toward the major thrust side

Proper installation orientation is crucial for engine performance.

Question 31

What two piston ring measurements must be made during a rebuild?

Answer 31

End gap and side clearance

Accurate measurements are essential for ensuring engine efficiency and longevity.

Question 32

What is the main purpose of the oil ring?

Answer 32

Control the amount of oil on the cylinder walls

It plays a critical role in engine lubrication and performance.

Question 33

How should ring end gaps be positioned on each piston?

Answer 33

Staggered evenly apart

This positioning helps to maintain effective sealing and performance.

Question 34

What are the two general types of ring compressors?

Answer 34

Fixed and adjustable

Each type serves different purposes during engine assembly.