190201e

Question 1

Why must cylinder ring ridges must be removed before removing the piston and connecting rod?

Answer 1

The piston rings will catch on the rings, making it difficult to remove. If the ridges are not removed damage could occur to the piston and/or cylinder.

Question 2

What are two safety precautions to take while using rotary wire brush, when removing carbon buildup in a cylinder?

Answer 2

• Where proper PPE

- Make sure the brush is suitable for the tool being used

Question 3

At what piston position, should the piston and rod be removed at?

Answer 3

Bottom Dead Center (BDC)

Question 4

Why is it necessary to remove piston cooling nozzles (some engines) when servicing the pistons?

Answer 4

It prevents damage to the cooling nozzles.

Question 5

When removing piston rings, what is the purpose of a ring expander?

Answer 5

The ring expander opens the piston rings just enough to slide up off the piston, thus preventing any damage to the rings and piston.

Question 6

What parts of a piston should not be bead blasted?

Answer 6

All parts of the piston should be avoided, except for the crown, dome, and alloy ring grooves (aluminum pistonss).

Question 7

What care should be taken when scraping carbon out of piston ring grooves?

Answer 7

Care should be taken to ensure metal is not scraped off with the carbon

Question 8

What tool is used to properly measure the ware in a KEYSTONE piston ring groove?

Answer 8

A ring groove wear gauge

Question 9

Pistons should be visually inspected for sings of what?

Answer 9

• Cracking on the crown
• Cracking in the piston ring bore
• Scoring/wear on the skirt
• Erosion in the ring grooves
• De-bonding of inserts (alloy ring grooves in aluminum pistons)

Question 10

A piston skirt is measured about midway down, and at what angle to the piston pin bore?

Answer 10

90°

Question 11

What are three problems that will occur as a result of worn piston ring grooves?

Answer 11

• Poor sealing will occur, resulting in blow by
• Rings will break due to excess movement
• Oil consumption will occur due to improper sealing

Question 12

Calculate the piston clearance:

Piston skirt diameter - 4.9985”
Cylinder bore diameter - 5.0017”

Answer 12

Clearance = 5.0017" - 4.9985"
Clearance = 0.0032"

Question 13

If a piston is installed with insufficient clearance between the skirt and cylinder wall, what would a likely outcome be?

Answer 13

Scuffing and scoring would occur, and eventual piston seizure. This is a result of the tight fit, improper lubrication, and excessive heat buildup.

Question 14

Piston PINS should be measured to determine:

Answer 14

Minimum outside dimension and out of round. The minimum dimension will give a good indication of pin wear, when compared to original specs.

Question 15

Calculate the piston pin clearance:

Piston pin diameter - 2.4997”
Piston pin bore diameter - 2.5012”

Answer 15

Pin clearance = 2.5012” - 2.4997”

Pin clearance = 0.0015”

Question 16

What methods can be used to check a connecting rod for cracks?

Answer 16

• Visual inspection (naked eye)
• Dye check
• Magnetic particle check
• Fluorescent magnetic particle (Magnaflux)

Question 17

What are the three measurements that must be made to determine the condition of the large end bore, on a connecting rod?

Answer 17

• Bore size
• Out of round
• Taper

Question 18

What will happen if a connecting rod is bent?

Answer 18

• Decreased engine efficiency due to a loss of compression (reduced compression ratio)
• Uneven wear on the piston and its components

Question 19

Unless otherwise stated, what is the proper position to install a full floating piston snap ring?

Answer 19

The ends should point down, and sharp edge facing out.

Question 20

If a full floating piston has an interference fit at room temperature, how would you remove it?

Answer 20

Heat the piston to expand the bore, then remove the pin.

Question 21

Explain how to position a piston ring, in a cylinder bore, to measure end gap:

Answer 21

Push the piston ring into an unworn area of the cylinder bore, with the gap facing up. Rotate the ring so it is horizontal and completely touching the bore wall. If desired, use a piston (upside-down) to gently push against the ring, to ensure it is flat.

Question 22

What would happen if a piston ring was installed without sufficient end gap?

Answer 22

The ring would seize up in the bore, as there would not be enough excess room for heat expansion.

Question 23

Why are piston ring end gaps staggered before the piston is installed?

Answer 23

Proper staggering minimizes the amount of combustion pressure, combustion gas, and oil leakage getting past the rings.

Question 24

What is important to check when installing connecting rod bearing shells?

Answer 24

The alignment of the locating tangs and oil holes.

Question 25

Why must piston and connecting rod assemblies be properly aligned during installation?

Answer 25

To prevent contact with internal engine components.

Question 26

What is the gap called between the connecting rod and crankshaft web?

Answer 26

Connecting rod side clearance

Question 27

What are three common ways to torque connecting rod fasteners?

Answer 27

• Torque (to a numerical value)
• Torque and turn (to a predetermined degree value)
• Bolt stretch (to a predetermined bolt length)

Question 28

What is the purpose of bearing clearance?

Answer 28

To prevent the crankshaft from seizing, and ensure connecting rod movement.

Question 29

What check should be performed after torquing the fasteners to each connecting rod?

Answer 29

Check for proper clearance and free rotation.

Question 30

True or False:

When a RECTANGULAR piston ring groove is measured for wear, the smallest feeler gauge is used to feel for roughness (rough means worn out).

Answer 30

FALSE - The feeler gauge that is equal to maximum clearance should be used to see if the groove is worn out. There should be a slight drag, as smoothness is a sign of being worn out.

Question 31

*What is the precision tool used to measure connecting rod alignment?

Answer 31

Alignment Fixture - Take measurements with a good rod, then compare the questionable rod to those measurements to see if there is a variation.

Question 32

At what piston position should the piston and rod be installed at?

Answer 32

Bottom Dead Center