Deck 19: Engine Lower End and Lubrication System Theory

Question 1

13)Which of the following statements is LEAST-Likely true?

A) Friction occurs between the piston rings and cylinder walls.
B) Low-tension piston rings were introduced in the mid-1980s to improve fuel economy.
C) Compression rings account for about 60% of the total drag on a cylinder wall, and the oil ring accounts for 20%.
D) Cast iron rings are used in re-ring jobs when the cylinder walls have not been re-bored.

Answer 1

C

Question 2

8)All of the following statements are true EXCEPT:

A) copper-lined bearings are premium bearings.
B) some bearings are made of solid aluminum alloy.
C) multilayered bearings have steel backs with one or more layers of lining material.
D) dissimilar metals slide against each other with greater friction than similar metals.

Answer 2

D

Question 3

18)Journals that are offset from the main bearing journal centerline are called ____________________.

Answer 3

rod journals,crankpins

Question 4

4)The top piston ring is positioned as high as possible on the piston to increase piston slap, help ring durability, and lower emissions.

Question 5

15)Which of the following is LEAST-Likely true?

A) Engine intake manifold vacuum during deceleration increases with compression ratio.
B) Oil consumption decreases with engine speed.
C) An engine that uses a single drop of oil with every power stroke would use 1 quart of oil every 2 miles.
D) Actual oil consumption per power stroke in an average engine is from 1/1000 to 2/1000 of a drop.

Question 6

2)Bearing spread promotes better heat transfer and prevents the bearing from spinning in the bore.

Question 7

9)____ is where the measurement across the parting face is slightly larger than the diameter of the bearing bore.

A) Torsional vibration
B) Cam ground
C) Bearing spread
D) Bearing crush

Question 8

17)Heavy-duty engines and some vintage automotive engines use replaceable cylinder bores, called wet or dry ____________________.

Question 9

19)The top of a cylinder receives less lubrication, and it is subjected to the high pressure of the piston rings against the cylinder wall as the air-fuel mixture is ignited. This can result in ____________________ wear.

Question 10

16)The crankshaft assembly, the piston, and the rod are collectively referred to as the ____________________.

Question 11

5)To test a moly or chrome ring to see if it is ductile iron, simply twist it. If it is regular iron, it will break in two.

Question 12

20)A(n) ____________________ is designed to clear the crankshaft counterweights on engines with short strokes.

Question 13

1)Main caps are not interchangeable and must be returned to the same bearing bores from which they were removed.

Question 14

12)The part that will MOST-Likely be used to prevent the piston pin from sliding out and damaging the cylinder wall is the:

A) wrist pin
B) piston ring
C) compression ring
D) lock ring

Question 15

7)While discussing vibration dampers, Technician A says that four-cylinder engines usually have a pulley and a damper. Technician B says that four-cylinder engines usually have only a pulley and do not use a damper. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 16

10)While discussing bearing undersizes, Technician A says that undersized bearings are used when a crankshaft is reground. Technician B says that they are used on some new engines to compensate for errors in production. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 17

6)The crankshaft is pushed forward in the engine by pressure in the torque converter or by the release spring pressure of the clutch. Forward and backward movement is called ____.

A) end thrust
B) bearing spread
C) torsional vibration
D) bearing crush

Question 18

11)All of the following statements are true EXCEPT:

A) nearly all engines are left-hand engines.
B) when viewing the piston from the right-hand side, the piston pin will be offset to the left side of the piston.
C) a left-hand engine is one that turns counterclockwise when viewing the engine from the flywheel side.
D) when a left-hand engine has oil squirt holes on the connecting rods, the holes are to the right when the piston notches are facing forward.

Question 19

3)Inline engines often have each rod lubricate its own cylinder.

Question 20

14)An imbalance of 1/4 ounce (7 grams, or about one sheet of paper) at a 4" radius on a rotating part will MOST-Likely create forces of:

A) 7 lb. at 2,000 rpm
B) 20 lb. at 4,000 rpm
C) 68 lb. at 6,000 rpm
D) 117 lb. at 8,000 rpm

Question 21

23)An aluminum piston expands at about twice the rate of the cast-iron block. What can be done to control this expansion?

Question 22

22)The bearing surface has three primary properties that make it suitable for use in an engine: embeddability, conformability, and fatigue strength. Provide definitions for each of these properties.

Question 23

25)What is the difference between ductile iron rings and steel rings?

Question 24

21)Briefly discuss the three sources that subject bearings to normal loads.

Question 25

24)Compression rings are forced against the cylinder wall by combustion pressure at the top and back of the ring. What is the purpose of the second ring?